JP7060842B2 - Laminate Laminate - Google Patents

Description

The present invention relates to a laminate used in the packaging field of foods, pharmaceuticals, industrial products and the like. More specifically, it has excellent gas barrier properties, dimensional stability, processability, rupture resistance, and bending resistance, and is easily damaged by hard contents such as dry matter packaging and severe moisture such as retort sterilization. The present invention relates to a gas-barrier laminated laminate having excellent gas-barrier properties even in applications to be applied after heat treatment.

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, 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 ELs and electronic parts 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, the surface of a base film made of plastic is made of a metal thin film made of aluminum or the like and an inorganic oxide such as silicon oxide or aluminum oxide. A gas barrier laminate having an inorganic thin film formed is generally used. Among them, those having a thin film (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, and a mixture thereof are widely used because they are transparent and the contents can be confirmed. Further, since the inorganic thin film layer made of an inorganic oxide can be heated in a microwave oven, the demand for a range-compatible retort pouch is increasing.

Range-compatible retort pouches are required to have water resistance, heat resistance, and toughness (bag rupture resistance and pinhole resistance) at the same time. Generally, at least three layers or more of heat-sealing resin are dry-laminated on the content side) via an adhesive.

In the above-mentioned retort pouch configuration, the gas barrier layer is generally laminated on a polyester film located on the outside of the bag from the viewpoint of productivity and quality stability, and its barrier performance is also very good. (For example, Patent Document 1). However, when the polyamide film and the heat-sealing resin are laminated to form a three-layer structure, at least two or more adhesive layers and, in some cases, a printing layer are present inside the gas barrier layer, and polyester. Since the barrier layer having excellent gas barrier properties is present on the film side, there is a problem that the residual solvent in the adhesive or the ink is easily transferred to the content side in one way. Further, since the polyester film on which the barrier layer is laminated is hard and brittle, there is a problem that the bag is broken when the bag is dropped and the contents leak, and the pinhole resistance is poor.

On the other hand, there is also a conventional technique of laminating a gas barrier layer on a polyamide film as an intermediate layer (for example, Patent Document 2). In this case, since the barrier layer is closer to the inside, there is an advantage that the transfer of the solvent to the contents can be reduced. However, the gas barrier laminated film using a polyamide film as a base material is a polyester film due to the weakness of moisture resistance and heat adhesion due to the characteristics of the polyamide film, and the physical damage of the barrier layer due to expansion and contraction and wrinkles due to moisture absorption of the base material. Compared to the case of laminating on top, the barrier property (particularly moisture-proof property) may be insufficient, or the moisture-resistant heat-adhesive property may be weak, so that the hand-cutting property in a wet state in which moisture is present may be insufficient. In addition, the polyamide film is inferior in heat resistance to the polyester film, and has problems in processing such as heat shrinkage wrinkles easily when the coat is applied and dried.

On the other hand, by using the layer having the biaxially stretched multilayer film obtained by biaxially stretching the polyester resin layer and the multilayer film having the polyamide resin layer as the base layer of the transparent gas barrier film, the cost is low. A technique has been proposed in which a packaging material for boil treatment or retort treatment, which has excellent low elution and transparency, can be obtained (for example, Patent Document 3), but such conventional techniques include a polyester resin layer and a polyamide. Since it is easily peeled off at the interface between the based resin layers, there is a problem that the bag is easily broken when the bag is dropped and the contents are easily leaked.

Further, a biaxially stretched polybutylene composed of at least one of a polyester resin composition in which polyethylene terephthalate (PET) resin is blended in a range of 30% by weight or less with respect to polybutylene terephthalate resin or polybutylene terephthalate (PBT) resin. By forming a vapor-deposited film made of an inorganic oxide on a terephthalate-based film, biaxially stretched polybutylene having excellent compression resistance, impact resistance, and water resistance that can be used even under severe retort conditions of 130 ° C or higher. A technique for obtaining a terephthalate film has been known (for example, Patent Document 4). However, the film-forming method by tubular simultaneous biaxial stretching disclosed in the prior art has poor thickness accuracy due to the manufacturing method, and the plane orientation coefficient does not increase, so that the impact resistance is inferior. In addition, there is a problem that it is easily stretched and inferior in processability when processing such as an adhesive application process on a film. Further, since PBT has a lower glass transition temperature than PET, it has a characteristic that the film is easily stretched when tension is applied under high temperature. Therefore, when tension is applied while being heated in each processing step, the film base material is stretched and cracks are formed in the previously formed inorganic thin film layer, resulting in a problem that the barrier property of the obtained barrier film is deteriorated. was there.

In the above-mentioned Patent Documents 1, 3 and 4, the retort-resistant barrier performance has been studied, but the optimum film configuration and processing stability have not been studied. Further, in Patent Document 2, the retort barrier resistance is examined, but the moisture resistance and heat adhesion are not examined.

In this way, it is excellent in production stability, processing stability and economy during manufacturing, and can maintain excellent barrier properties, adhesiveness and toughness even after harsh wet heat treatment such as retort treatment. At present, a gas barrier laminated laminate having a film structure that can suppress solvent transfer to a product and has good hand-cutting property has not been obtained.

International release WO2016 / 136768 Japanese Patent No. 4857482 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, has excellent barrier properties, wrapping resistance, and bending resistance, and has sufficient hand-cutting property in a wet state in which water is present. Excellent barrier properties can be maintained even when used for packaging hard contents such as dry matter packaging, or for applications where severe moist heat treatment such as retort treatment is applied, and to the contents. The challenge was to provide a laminate with less transfer of residual solvent.

The laminated laminate of the present invention, which solves the above problems, has the following aspects.

(1) A laminated laminate in which a polyester film, a base material laminated film, and a heat-sealing resin are laminated in this order, and the base material laminated film has an inorganic thin film layer on at least one side of the base material layer and another. It is a laminated film laminated with or without a layer, and the base material layer is a biaxially stretched polyester film base material made of a resin composition containing at least 60% by mass of polybutylene terephthalate, and A laminated laminate characterized by simultaneously satisfying the following (a) and (b).
(a) The heat shrinkage rate at 150 ° C. in the longitudinal direction and the width direction of the substrate layer is 4.0% or less.
(b) The dimensional change rate at 200 ° C. with respect to the original length of the base material layer of the temperature dimensional change curve measured by using TMA (thermal mechanical analyzer) is 2% or less in the longitudinal direction of the base material layer.

(2) The laminated laminate according to (1), wherein a coating layer is provided between the base material layer and the inorganic thin film layer.

(3) The laminated laminate according to (1) or (2), wherein the inorganic thin film layer is a layer made of a composite oxide of silicon oxide and aluminum oxide.

(4) The laminated laminate according to (2) or (3), wherein the coating layer comprises a resin composition containing a resin having an oxazoline group.

The laminated laminate of the present invention has excellent barrier properties, rupture resistance, and bending resistance, has sufficient hand-cutting property in a wet state in the presence of water, and is used for packaging hard contents such as dry matter packaging. can do. Further, since it has excellent water resistance and adhesiveness, peeling does not occur even if harsh wet heat treatment such as retort treatment is performed, and there is no problem that the barrier property is deteriorated or the contents leak out. Further, since the intermediate layer is not polyamide but PBT having excellent moisture resistance, it is excellent in barrier property, moisture resistance, and hand-cutting property after wet heat treatment, and is also excellent in toughness as a base material. Further, since the intermediate layer serves as a barrier layer, the transfer of the residual solvent to the contents is small. Moreover, since the laminated film of the present invention can be easily manufactured with few processing steps, it is excellent in both economic efficiency and production stability, and it is possible to provide a gas barrier film having uniform characteristics.

The laminated laminate of the present invention has at least three or more layers in which a polybutylene terephthalate-based substrate laminated film is used as an intermediate layer, a polyester film is laminated on one surface, and a heat-sealable resin layer is laminated on the other surface. Has. Further, an inorganic thin film layer is provided on at least one side of the polybutylene terephthalate-based base film. This laminated film is referred to as a polybutylene terephthalate-based base material laminated film.

The present inventors use a polybutylene terephthalate-based biaxially stretched polyester film as a base material layer, and when an inorganic thin film layer is laminated on the base material layer to form a base material laminated film, the present inventors heat-shrink the base material layer. It was found that by setting the rate, constant load, and dimensional change rate under temperature within a specific range, it is difficult to deform even with respect to the tension and heating temperature applied in the processing process, and damage to the inorganic thin film layer can be suppressed. rice field. Further, by using a polybutylene terephthalate-based biaxially stretched polyester film having excellent moisture resistance as the intermediate layer instead of the polyamide layer as the above-mentioned three or more layers, the barrier property, the moisture resistance, and the hand-cutting property after the wet heat treatment are used. The present inventors have found that the intermediate layer is a barrier layer, which is excellent in excellent toughness as a base material and also has an effect of reducing the transfer of residual solvent to the contents. The present invention has been completed.

Hereinafter, the base material laminated film and each layer laminated on the base material laminated film will be described in order.

[Polyester film]
As the polyester film used in the present invention, for example, a film (uniaxially stretched film or biaxially stretched film) obtained by melt-extruding a plastic polyester and, if necessary, stretching, cooling, and heat-fixing in the longitudinal direction and / or the width direction. ) Can be used. Among these, polyethylene terephthalate or a copolymer obtained by copolymerizing polyethylene terephthalate with other components is preferable in terms of heat resistance, stepping stability, and transparency, and a biaxially stretched polyethylene terephthalate film is particularly preferable.

As the polyester film, a film having an arbitrary film thickness can be used according to a desired purpose and application such as mechanical strength and transparency, and the film thickness is not particularly limited, but is preferably 5 to 250 μm. When used as a packaging material, it is preferably 10 to 60 μm.
The transparency of the polyester film is not particularly limited, but when it is used as a packaging material for which transparency is required, a polyester film having a light transmittance of 50% or more is preferable.

The polyester film may be a single-layer film made of one kind of polyester, or may be a laminated film in which two or more kinds of polyester films are laminated. The type of laminated body, the number of laminated bodies, the laminating method, and the like in the case of forming a laminated film are not particularly limited, and can be arbitrarily selected from known methods according to the purpose.
Further, the polyester film may be subjected to surface treatment such as corona discharge treatment, glow discharge, flame treatment, and surface roughening treatment as long as the object of the present invention is not impaired, and a known anchor coating treatment may be applied. , Printing, decoration, etc. may be applied.

[Base layer]
The base material layer used in the present invention is a biaxially stretched film made of a resin composition containing 60% by mass or more of PBT. The content of PBT is preferably 70% by mass or more. If the content of PBT is less than 60% by mass, the impact strength or pinhole resistance is lowered, and the film characteristics are not sufficient.
As the dicarboxylic acid component, PBT preferably contains terephthalic acid in an amount of 90 mol% or more, more preferably 95 mol% or more, still more preferably 98 mol% or more, and most preferably 100 mol%. The glycol component 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 the diol.

The resin composition used in the present invention can contain a polyester other than PBT for the purpose of adjusting the film-forming property at the time of biaxial stretching and the mechanical properties of the obtained film.
Examples of the polyester other than PBT include at least one polyester selected from the group consisting of PET, polyethylene naphthalate, polybutylene naphthalate and polypropylene terephthalate, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid and cyclohexanedicarboxylic acid. PBT, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol, 1, Examples thereof include PBT in which at least one diol component selected from the group consisting of 5-pentanediol, 1,6-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 preferably 40% by mass or less, more preferably 30% by mass or less. If the amount of polyester other than PBT added exceeds 40% by mass, the mechanical properties of polybutylene terephthalate will be impaired, impact strength, pinhole resistance, or bag breakage resistance will be insufficient, and transparency and gas barrier will be insufficient. Problems such as deterioration of sex may occur.

The lower limit of the intrinsic viscosity of polybutylene terephthalate (PBT) 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 polybutylene terephthalate (PBT) is less than 0.9 dl / g, the intrinsic viscosity of the film obtained by forming a film decreases, and the puncture strength, impact strength, pinhole resistance, or fracture resistance is reduced. The bag property may be reduced.
The upper limit of the intrinsic viscosity of polybutylene terephthalate 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 polybutylene terephthalate 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 polybutylene terephthalate is extruded at a higher temperature, decomposition products may be easily generated.

If necessary, the resin composition may contain conventionally known additives such as lubricants, stabilizers, colorants, antistatic agents, and ultraviolet absorbers.
As the lubricant type, 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 lubricant concentration is preferably 100 ppm, more preferably 500 ppm, still more preferably 800 ppm. If it is less than the above, the slipperiness of the base film layer may decrease. The upper limit of the lubricant concentration is preferably 20000 ppm, more preferably 10000 ppm, still more preferably 1800 ppm. If it exceeds the above, transparency may decrease.

The base material layer in the present invention is preferably made of a resin having the same composition over the entire area.
In the base material layer in the present invention, the lower limit of the base material layer thickness is preferably 3 μm, more preferably 5 μm, and even more preferably 8 μm. When it is 3 μm or more, the strength as a base film layer becomes sufficient.
The upper limit of the base film layer thickness 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.

The upper limit of the heat shrinkage rate after heating at 150 ° C. for 15 minutes in the longitudinally stretched (longitudinal) direction (MD) and the transversely stretched (width) direction (TD) of the biaxially stretched polyester film constituting the base material layer in the present invention is preferable. Is 4.0%, more preferably 3.0%, still more preferably 2%. If the upper limit is exceeded, the inorganic thin film layer may be cracked due to the dimensional change of the base film layer caused by the protective film forming process or the high temperature treatment such as retort sterilization treatment, and the gas barrier property may be deteriorated. Pitch deviation may occur due to dimensional changes during processing.

The lower limit of the heat shrinkage after heating at 150 ° C. for 15 minutes in the longitudinal stretching direction (MD) and the transverse stretching direction (TD) of the biaxially stretched polyester film constituting the base material layer in the present invention is preferably −2.0%. Is. Even if it falls below the above lower limit, the effect of improvement cannot be obtained any more (saturated), and it may become mechanically brittle.

In the temperature dimensional change curve in the longitudinal direction measured by using TMA (thermal mechanical analyzer) of the biaxially stretched polyester film constituting the base material layer in the present invention, the dimensional change rate at 200 ° C. with respect to the original length of the film is 2%. The following is preferable. If it exceeds 2%, the inorganic thin film layer may be cracked due to the dimensional change of the base material layer caused by the high temperature treatment such as retort sterilization treatment, and not only the gas barrier property may be deteriorated, but also the dimensional change during processing such as printing. As a result, pitch deviation may occur.
It is more preferably 1.5% or less, further preferably 1.0% or less, still more preferably 0.5% or less, and particularly preferably 0% or less.

The lower limit of the impact strength of the biaxially stretched polyester film constituting the base material layer in the present invention is preferably 0.05 J / μm. If it is 0.05 J / μm or more, the strength becomes sufficient when used as a bag.
The upper limit of the impact strength of the biaxially stretched polyester film constituting the base material layer in the present invention is preferably 0.2 J / μm. Even if the upper limit is exceeded, the effect of improvement cannot be obtained any more (saturated).

The lower limit of the vertical orientation (ΔNx) of the biaxially stretched polyester film constituting the base material layer 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 the base material layer, and not only the bag breaking resistance may be deteriorated, but also an inorganic thin film layer is provided on the base material layer to form a laminated film. In this case, the tension and temperature applied during the formation of the inorganic thin film layer make it easy to stretch, and the inorganic thin film layer is cracked, so that the gas barrier property may be deteriorated.

The upper limit of the vertical orientation (ΔNx) of the biaxially stretched polyester film constituting the base material layer in the present invention is preferably 0.09, more preferably 0.085, and further preferably 0.08. Within the above range, the mechanical properties of the base material layer and the straight-line tearability are more preferable.

The upper limit of the haze per thickness of the biaxially stretched polyester film constituting the base material layer in the present invention is preferably 0.66% / μm, more preferably 0.60% / μm, and further preferably 0. It is 53% / μm. When printing is applied to a base material layer having a ratio of 0.66% / μm or less, the quality of printed characters and images is improved.

Further, the biaxially stretched polyester film constituting the base material layer in the present invention may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, and surface roughening treatment as long as the object of the present invention is not impaired. Further, known anchor coating treatment, printing, decoration and the like may be applied.

Next, a manufacturing method for obtaining a biaxially stretched polyester film constituting the base material layer according to the present invention will be specifically described. It is not limited to these.

First, the film raw material made of the above-mentioned resin composition is dried or hot-air dried. Next, the raw materials are weighed, mixed, supplied to the 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 to apply a voltage to an electrode installed near the surface opposite to the surface of the resin sheet in contact with the rotating metal roll in the vicinity of the molten 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 decomposition of the resin proceeds and the film becomes brittle.

When casting the molten polyester resin onto an extruded cooling roll, it is preferable to reduce the difference in crystallinity in the width direction. Specific methods for this include extruding the molten polyester resin and casting the raw materials having the same composition in multiple layers at the time of casting, and further lowering the cooling roll temperature to a low temperature.
Since the crystallization rate of PBT resin is high, crystallization proceeds even during casting.
At this time, when cast in a single layer without multi-layering, the spherulite grows into a large-sized spherulite because there is no barrier that can suppress the growth of the crystal. As a result, the yield stress of the obtained unstretched sheet becomes high, and not only is it easy to break during biaxial stretching, but also the impact strength, pinhole resistance, or bag breaking resistance of the obtained biaxially stretched film is improved. The film will be inadequate. On the other hand, by laminating the same resin in multiple layers, the stretching stress of the unstretched sheet can be reduced, and the subsequent biaxial stretching can be stably performed.

A method of extruding a molten polyester resin and casting by layering raw materials having the same composition at the time of casting is specifically a step of melting a resin composition containing 60% by weight or more of PBT resin to form a molten fluid (a step of forming a molten fluid. 1), a step of forming a laminated fluid having a laminated number of 60 or more composed of the formed molten fluid (2), the formed laminated fluid is discharged from a die and brought into contact with a cooling roll to be solidified to form a laminated unstretched sheet. It has at least a step (3) of forming and a step (4) of biaxially stretching the laminated unstretched sheet.
Another step may be inserted between the steps (1) and the step (2), and between the steps (2) and the step (3). For example, a filtration step, a temperature changing step, or the like may be inserted between the steps (1) and the step (2). Further, a temperature changing step, a charge adding step, or the like may be inserted between the steps (2) and the step (3). However, there must be no step between the step (2) and the step (3) to break the laminated structure formed in the step (2).

In the step (1), the method of melting the polyester resin composition to form a molten fluid is not particularly limited, but a preferred method includes a method of heating and melting using a single-screw extruder or a twin-screw extruder. Can be done.

The method for forming the laminated fluid in the step (2) is not particularly limited, but a static mixer and / or a multilayer feed block is more preferable from the viewpoint of convenience of equipment and maintainability. Further, from the viewpoint of uniformity in the sheet width direction, those having a rectangular melt line are more preferable. It is more preferred to use a static mixer or multi-layer feed block with rectangular melt lines. The resin composition composed of a plurality of layers formed by merging the plurality of resin compositions may be passed through one or more of a static mixer, a multilayer feed block, and a multilayer manifold.

The number of theoretical stacks in the step (2) is preferably 60 or more. The lower limit of the theoretical stacking number is more preferably 500. If the number of theoretical layers is too small, or the distance between the layer interfaces becomes long and the crystal size becomes too large, the effect of the present invention tends to be ineffective. In addition, the crystallinity near both ends of the sheet increases, the film formation becomes unstable, and the transparency after molding may decrease. The upper limit of the number of theoretical stacks in the step (2) 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 the lamination in the step (2) is performed by a static mixer, the theoretical number of laminations can be adjusted by selecting the number of elements of the static mixer. A 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 laminated. Therefore, when a high-viscosity fluid is passed through a static mixer having n elements, a laminated fluid having a theoretical stacking number of N = 2n is formed.

A typical static mixer element has a structure in which a rectangular plate is twisted 180 degrees, and depending on the direction of twist, there are a right element and a left element, and the dimensions of each element are 1.5 times longer than the diameter. It is basic. The static mixer that can be used in the present invention is not limited to such a static mixer.

When the lamination in the step (2) is performed by the multilayer feed block, the theoretical number of laminations can be adjusted by selecting the number of divisions / laminations of the multilayer feed block. Multiple multilayer feed blocks can be installed in series. Further, the high-viscosity fluid itself supplied to the multilayer feed block can be used as the laminated fluid. For example, when the number of laminated high-viscosity fluids supplied to the multilayer feed block is p, the number of divided / stacked multilayer feed blocks is q, and the number of installed multilayer feed blocks is r, the number of stacked fluids N is N = p. It becomes × qr.

In the step (3), the laminated fluid is discharged from the die and brought into contact with the cooling roll to be solidified.
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 upper limit of the cooling roll temperature 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. At this time, the thickness of the unstretched sheet is preferably in the range of 15 to 2500 μm.
The unstretched sheet having a multilayer structure described above has at least 60 layers or more, preferably 250 layers or more, and more preferably 1000 layers or more. If the number of layers is small, the effect of improving stretchability is lost.

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. After biaxial stretching, it is preferable to provide heat fixing (heat treatment) and relaxing (relaxation) steps.

The lower limit of the stretching temperature in the longitudinal stretching direction (hereinafter abbreviated as MD) is preferably 55 ° C, more preferably 60 ° C. If the temperature is 55 ° C. or higher, fracture is unlikely to occur. Further, since the degree of vertical orientation of the film does not become too strong, shrinkage stress during the heat fixing treatment can be suppressed, and a film with less distortion of molecular orientation in the width direction can be obtained. The upper limit of the MD stretching temperature 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, so that the mechanical properties of the film do not deteriorate.

The lower limit of the MD draw ratio is preferably 2.8 times, and particularly preferably 3.0 times. If it is 2.8 times or more, the degree of vertical orientation becomes large and the dimensional change rate at 200 ° C. becomes small. Therefore, when the inorganic thin film layer and the protective layer are provided on the base film layer, when the protective film is formed. The tension applied to the base film layer also makes it difficult to stretch, and the inorganic thin film layer is difficult to crack, so that the gas barrier property is improved. In addition, the mechanical properties and thickness unevenness of the film are improved.
The upper limit of the MD draw ratio 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 lateral orientation of the film does not become too strong, the shrinkage stress during the heat fixing process does not become too large, and the distortion of the lateral molecular orientation of the film becomes small, resulting in As a result, the straight tearability in the longitudinal direction is improved. Moreover, the effect of improving the mechanical strength and the thickness unevenness is saturated in this range.

The lower limit of the stretching temperature in the transverse stretching direction (hereinafter abbreviated as TD) is preferably 60 ° C., and if it is 60 ° C. or higher, fracture may be less likely to occur. The upper limit of the TD stretching temperature is preferably 100 ° C., and when it is 100 ° C. or lower, the degree of lateral orientation increases and the mechanical properties are improved.

The lower limit of the TD stretch ratio 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 lateral orientation does not become too weak, and the mechanical properties and thickness unevenness are improved. The upper limit of the TD stretch ratio is preferably 5 times, more preferably 4.5 times, and particularly preferably 4.0 times. When it is 5.0 times or less, the effect of improving the mechanical strength and the thickness unevenness is maximized (saturated) even in this range.

The lower limit of the TD heat fixing temperature is preferably 200 ° C, more preferably 205 ° C. When the temperature is 200 ° C. or higher, the heat shrinkage rate in the MD direction and the TD direction of the film can be 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 TD heat fixing temperature is preferably 240 ° C., and when it is 240 ° C. or lower, the base film layer does not melt and is less likely to become brittle.

The heat shrinkage in the TD direction can be reduced by TD relaxation. The lower limit of the TD relaxation rate is preferably 0.5%. If it is 0.5% or more, it may be difficult for fracture to occur during heat fixing. The upper limit of the TD relaxation rate is preferably 5%. When it is 5% or less, the shrinkage in the longitudinal direction at the time of heat fixing becomes small, and as a result, the distortion of the molecular orientation at the end of the film becomes small, and the straight tearability is improved. In addition, slackening of the film is unlikely to occur, and uneven thickness is unlikely to occur.

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

In the laminated laminate of the present invention, a coating layer can be provided between the base material layer and the inorganic thin film layer for the purpose of ensuring the barrier property and the laminating strength after the retort treatment.
The coating layer provided between the base material layer and the inorganic thin film layer includes urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resins, epoxy-based, isocyanate-based, and resin. Examples thereof include those to which a curing agent such as melamine is added. Examples of the solvent (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. Examples thereof include polyhydric alcohol derivatives such as glycol monomethyl ether. The resin composition used for these coating 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. By adding the silane coupling agent, the laminating strength after the retort treatment is further improved.

Among the resin compositions used for the coating layer, it is preferable to use a resin containing an oxazoline group. 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 coating layer can react with the carboxylic acid terminal generated by the hydrolysis of the base film and the coating layer to form a crosslink.

A polyester resin, a urethane resin, or an acrylic resin may be mixed with the coating layer for the purpose of improving the adhesion to the base material layer. In particular, urethane resin is used from the aspect of close contact. Acrylic resin is preferable from the viewpoint of water resistance.

The method for forming the early coating layer is not particularly limited, and 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 biaxially stretched polyester film substrate constituting the substrate layer, 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. It is preferable to feed it into the stretching step in the perpendicular direction and dry it 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. A method in which a sequential biaxial stretching method is adopted, the film after MD stretching is coated, and then TD stretching is performed is more preferable.

In the present invention, the adhesion amount of the coating layer is preferably 0.010 to 0.200 g / m ² . As a result, the coating layer can be uniformly controlled, and as a result, the inorganic thin film layer can be densely deposited. In addition, the cohesive force inside the coating layer is improved, and the adhesion between each layer of the base material layer-coating layer-inorganic thin film layer is also increased, so that the water resistance and adhesion of the coating layer can be enhanced. The adhesion amount of the coating layer is preferably 0.015 g / m 2 or more, more preferably 0.020 g / m ² or more, still more preferably 0.025 g / m ² or more, and preferably 0.190 g / m ² or less. It is more preferably 0.180 g / m ² or less, still more preferably 0.170 g / m ² or less. If the adhesion amount of the coating layer exceeds 0.200 g / m ² , the cohesive force inside the coating layer becomes insufficient, and good adhesion may not be exhibited. In addition, since the uniformity of the coating layer is also lowered, defects may occur in the inorganic thin film layer, and the gas barrier property may be lowered. Moreover, the manufacturing cost becomes high, which is economically disadvantageous. On the other hand, if the film thickness of the coating layer is less than 0.010 g / m ² , the substrate may not be sufficiently coated, and sufficient gas barrier properties and interlayer adhesion may not be obtained.

The resin composition for the coating layer contains various known inorganic and organic additives such as an antistatic agent, a slip agent, and an anti-blocking agent, if necessary, as long as the present invention is not impaired. May be good.

[Inorganic thin film layer]
In the base material laminated film of the present invention, an inorganic thin film layer is laminated. The inorganic thin film layer is a thin film made of an inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can be made into a thin film, but from the viewpoint of gas barrier properties, silicon oxide (silica), aluminum oxide (alumina), and a mixture of silicon oxide and aluminum oxide (composite oxide). ) And the like are preferably mentioned. In particular, a composite oxide of silicon oxide and aluminum oxide is preferable from the viewpoint of achieving both flexibility and denseness of the thin film layer. In this composite oxide, the mixing ratio of silicon oxide and aluminum oxide is preferably in the range of 20 to 70% by mass of Al in terms of the mass ratio of the metal content. If the Al concentration is less than 20% by mass, the barrier property may be lowered, while if it exceeds 70% by mass, the inorganic thin film layer tends to be hard, and the film tends to be hardened during secondary processing such as printing or laminating. May be destroyed and the barrier property may be reduced. The silicon oxide referred to here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and the aluminum oxide is various aluminum oxides such as AlO and Al ₂ O ₃ or a mixture thereof.

The 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. However, it is 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 an inorganic thin film layer will be described using a silicon oxide / aluminum oxide thin film as an example. For example, when the vacuum vapor deposition method is adopted, a mixture of SiO ₂ and Al ₂ O ₃ or a mixture of SiO ₂ and Al is preferably used as the vapor deposition raw material. 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 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. 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-film-deposited body, heating / cooling, and the like can be similarly changed when the sputtering method or the CVD method is adopted.

In the present invention, a protective layer may be provided on the inorganic thin film layer, if necessary. The inorganic thin film layer is not a completely dense film, but is dotted with minute defects. By applying the protective layer resin composition on the inorganic thin film layer to form the protective layer, the resin in the protective layer resin composition permeates the defective portion of the inorganic thin film layer, and as a result, the gas barrier property is stable. The effect of doing is obtained. In addition, since deterioration of the barrier property when the print layers are laminated can be suppressed, printing becomes possible. In addition, by using a material having a gas barrier property for the protective layer itself, the gas barrier performance of the laminated film can be greatly improved.

The protective layer formed on the surface of the laminated film of the present invention includes urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resins, and epoxy-based, isocyanate-based, and melamine-based resins. Examples include those to which a curing agent is added. Examples of the solvent (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. Examples thereof include polyhydric alcohol derivatives such as glycol monomethyl ether.

[Lamination with heat-sealing resin layer]
The laminated laminate of the present invention needs to contain a heat-sealing resin layer called a sealant. The heat-sealable resin layer is usually provided on the inorganic thin film layer side (on the protective layer surface when the protective layer is formed on the inorganic thin film layer), but is provided on the outside of the base film (the surface opposite to the coating layer forming surface). It may be provided in. The heat-sealing resin layer is usually formed by an extrusion laminating method or a dry laminating method using a sealant film. 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. , Ethethylene-α-olefin random copolymer, ionomer resin and the like can be used. The thickness of the heat-sealing resin layer is preferably 20 μm or more, more preferably 25 μm or more, still more preferably 30 μm or more, preferably 80 μm or less, more preferably 75 μm or less, still more preferably 70 μm or less. If the thickness is 20 μm or less, the productivity deteriorates. On the other hand, if it is 80 μm or more, the cost increases and the transparency also deteriorates.

[Other layers]
In the laminated laminate of the present invention, at least one or more layers of a printing layer, another plastic base material and / or a paper base material may be laminated between the polyester film and the base material layer.

[Adhesive layer]
As the adhesive layer used in the present invention, a general-purpose laminating adhesive can be used. For example, poly (ester) urethane type, polyester type, polyamide type, epoxy type, poly (meth) acrylic type, polyethyleneimine type, ethylene- (meth) acrylic acid type, polyvinyl acetate type, (modified) polyolefin type, polybutagen. (No) solvent-based, aqueous-based, and heat-melting type adhesives containing based, wax, casein, etc. as the main components can be used. Among these, urethane-based or polyester-based materials are preferable in consideration of moisture and heat resistance that can withstand retort treatment and flexibility that can follow dimensional changes of each base material. Examples of the method for laminating the adhesive layer include a direct gravure coating method, a reverse gravure coating method, a kiss coating method, a die coating method, a roll coating method, a dip coating method, a knife coating method, a spray coating method, a fonten coating method, and the like. The coating amount after drying is preferably 1 to 8 g / m2 because it can be applied by the above method and exhibits sufficient adhesiveness after retorting. It is more preferably 2 to 7 g / m2, still more preferably 3 to 6 g / m2. If the coating amount is less than 1 g / m2, it becomes difficult to bond the entire surface, and the adhesive strength is lowered. On the other hand, if it exceeds 8 g / m2, it takes time to completely cure the film, unreacted substances tend to remain, and the adhesive strength is lowered.

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, UV absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, 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.

On the other hand, as the other plastic base material or paper base material, paper, polyester resin, biodegradable resin and the like are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminated body. Further, in order to obtain a film having excellent mechanical strength, a stretched film such as a biaxially stretched polyester film is preferable.

It is preferable that the laminated body of the present invention has an oxygen permeability of 20 ml / m2 · d · MPa or less under 23 ° C. × 65% RH conditions before and after the retort treatment from the viewpoint of exhibiting good gas barrier properties. .. Further, by controlling the above-mentioned inorganic thin film layer component / adhesion amount, it can be preferably 15 ml / m2 · d · MPa or less, more preferably 13 ml / m2 · d · MPa or less. If the oxygen permeability exceeds 20 ml / m2 · d · MPa, it becomes difficult to meet applications requiring high gas barrier properties. On the other hand, if the oxygen permeability before and after the retort treatment is less than 1 ml / m2 · d · MPa, the barrier performance is excellent, but the residual solvent is difficult to permeate to the outside of the bag, and the residue is relatively transferred to the contents. It is not preferable because the amount may increase. The preferable lower limit of oxygen permeability is 1 ml / m2 · d · MPa or more.

The laminated body of the present invention preferably has a water vapor transmission rate of 2.0 g / m2 · d or less under 40 ° C. × 90% RH conditions before and after the retort treatment, from the viewpoint of exhibiting good gas barrier properties. Further, by controlling the above-mentioned inorganic thin film layer component / adhesion amount, it can be preferably 1.5 g / m2 · d or less, more preferably 1.0 g / m2 · d or less. If the water vapor transmission rate exceeds 2.0 g / m2 · d, it becomes difficult to meet applications that require high gas barrier properties. On the other hand, if the water vapor transmission rate before and after the retort treatment is less than 0.1 g / m2, the barrier performance is excellent, but the residual solvent is difficult to permeate to the outside of the bag, and the amount of transfer to the contents is relatively large. It is not preferable because it may increase. The preferable lower limit of the water vapor transmission rate is 0.1 g / m2 · d or more.

The laminate of the present invention preferably has a watered laminate strength of 2.0 N / 15 mm or more, more preferably 2.5 N / 15 mm or more, and further preferably 2.5 N / 15 mm or more under the conditions of 23 ° C. × 65% RH before and after the retort treatment. It is preferably 3.0 N / 15 mm or more. If the laminating strength is less than 2.0 N / 15 mm, peeling may occur due to a bending load or the contents of the liquid, and the barrier property may be deteriorated or the contents may leak out. Further, there is a possibility that the hand-cutting property may be deteriorated.

The laminate of the present invention preferably has a tear strength of 2.0 N or less, more preferably 1.8 N or less, still more preferably 1.6 N or less in the evaluation of hand-cutting property. When the tear strength is 2.0 N or less, when the consumer actually tears by hand, stress propagation between each layer is easy and the film can be torn with a stable force, resulting in good hand-cutting property. A film is obtained. Further, when the tear strength is 2.0 N or more, stress propagation between each layer is difficult, stress is applied more as the tear is made, and there is a possibility that the hand-cutting property is deteriorated.

In the laminated body of the present invention, the number of pinholes in the evaluation of pinhole resistance is preferably 18 or less, more preferably 16 or less, still more preferably 14 or less. When the number of pinholes is 18 or less, there is less possibility that the bag will be broken and the contents will leak when the bag is dropped or bent. On the other hand, if the number of pinholes is 18 or more, the strength of the bag is insufficient, and the bag may be broken and the contents may leak.

Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is naturally not limited to the following Examples. Unless otherwise specified, "%" means "% by mass" and "part" means "part by mass".
The evaluation method used in the present invention is as follows.

-Thickness of the base material layer Measured using a dial gauge in accordance with JIS K7130-1999 A method.

-Vertical orientation of the base material layer ΔNx
About the sample The refractive index (Nx) in the longitudinal direction of the film and the refractive index (Ny) in the width direction are measured by the Abbe refractometer using the sodium D line as the light source by the JIS K 7142-1996 A method, and the formula (2) is calculated. The vertical orientation degree ΔNx was calculated by
Vertical orientation (ΔNx) = Nx- (Ny + Nz) / 2 (1)

Heat shrinkage rate of the base material layer The dimensional change test described in JIS-C-21151-2006.21 except that the heat shrinkage rate of the polyester film constituting the base material layer was set to a test temperature of 150 ° C. and a heating time of 15 minutes. Measured by method. The test piece was used as described in 21.1 (a).

Dimensional change rate of the base material layer at 200 ° C. Using a TMA (thermal mechanical analyzer) manufactured by Shimadzu Corporation, the temperature was raised from room temperature to 200 ° C., and the longitudinal direction of the polyester film constituting the base material layer was measured. However, the rate of temperature rise 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 tension was 100 mN.
The dimensional change rate (%) at 200 ° C. of the obtained temperature change curve was read.

-Preparation of Laminated Laminates for Evaluation A urethane-based two-component curable adhesive (Mitsui Kagaku) was applied to the surface of the base material laminated film obtained in Examples 1 to 6 and Comparative Examples 1 to 5 on the side opposite to the inorganic thin film layer surface. A 12 μm thick polyester film (Made by Toyobo Co., Ltd. “Takelac (registered trademark) A525S” and “Takenate (registered trademark) A50” in a ratio of 13.5: 1 (mass ratio)). E5100 ") is laminated by the dry laminating method, and a 70 μm-thick unstretched polypropylene film (“P1147” manufactured by Toyobo Co., Ltd.) is formed as a heat-sealable resin layer on the inorganic thin film layer surface of the laminated film using the same adhesive. By laminating by a dry laminating method and aging at 40 ° C. for 4 days, a laminated laminated film for evaluation (hereinafter, also referred to as "laminated laminated body A") was obtained. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was about 4 μm.
On the other hand, a polyester film having a thickness of 12 μm (“E5100” manufactured by Toyobo Co., Ltd.) was bonded to the inorganic thin film layer surface of the base material laminated film obtained in Comparative Example 6 by a dry laminating method using the above-mentioned adhesive, and further. An unstretched polypropylene film (“P1147” manufactured by Toyobo Co., Ltd.) with a thickness of 70 μm was bonded to the opposite surface of the polyester film as a heat-sealing resin layer using the same adhesive by a dry laminating method, and aged at 40 ° C. for 4 days. To obtain a laminated laminate for evaluation (hereinafter, also referred to as "laminated laminate B").

(6) Pinhole resistance of the 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 heated to 23. It was conditioned by leaving it for 24 hours or more under the condition of a relative humidity of 50% at ° C. After that, the rectangular test film is wound to form a cylinder with a length of 20.32 cm (8 inches). Then, one end of the cylindrical film is fixed to the outer periphery 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 formed. The other end of the tester was fixed to the outer periphery 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 in parallel, and subsequently 6.4 cm (without rotation). 2.5 inches) After going straight, a one-cycle bending test in which those movements are performed in the opposite direction 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 part within 17.8 cm (7 inches) × 27.9 cm (11 inches) excluding the fixed head and the fixed part on the outer circumference of the movable head of the tested film was measured (that is,). The number of pinholes per 497 cm2 (77 square inches) was measured).

(7) Evaluation method of hand-cutting property of laminated laminate (tear strength)
The laminated laminate produced in (5) above was cut into a test piece having a width of 25 mm and a length of 300 mm in the width direction (TD direction) and the length direction (MD direction) of the base film, respectively, at a temperature of 23 ° C. The tear strength was measured using a Tencilon universal material tester (“Tencilon UMT-II-500 type” manufactured by Toyo Baldwin Co., Ltd.) under a condition of a relative humidity of 65%. The tear strength was measured by setting the tear speed to 50 mm / min, making a 10 mm notch in the length direction at a width of 12.5 mm, immersing it in water for 10 seconds immediately before the measurement, and then measuring the tear strength.

(8) Oxygen permeability evaluation method For the laminated laminate produced in (5) above, an oxygen permeability measuring device (MOCON's "OX-TRAN (registered trademark) 1/50" is based on the JIS-K7126 B method. ]) Was used to measure the normal oxygen permeability in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH. The oxygen permeability was measured in the direction in which oxygen permeates from the base film side of the laminated laminate to the heat-sealable resin layer side. On the other hand, the laminated laminate prepared in (5) above was subjected to a wet heat treatment for holding it in hot water at 120 ° C. for 30 minutes, dried at 40 ° C. for 1 day (24 hours), and after the obtained wet heat treatment. Oxygen permeability (after retort) was measured in the same manner as above for the laminated laminate of.

(9) Evaluation method of water vapor transmission rate For the laminated laminate prepared in (5) above, a water vapor transmission rate measuring device (“PERMATRAN-W 3/33 MG” manufactured by MOCON) was used in accordance with the JIS-K7129B method. The water vapor transmission rate under normal conditions was measured in an atmosphere of a temperature of 40 ° C. and a humidity of 90% RH. The water vapor transmission rate was measured in the direction in which water vapor permeated from the heat-sealing resin layer side of the laminated laminate toward the base film side.
On the other hand, the laminated laminate prepared in (5) above was subjected to a wet heat treatment for holding it in hot water at 120 ° C. for 30 minutes, dried at 40 ° C. for 1 day (24 hours), and after the obtained wet heat treatment. The water vapor transmission rate (after retort) was measured for the laminated laminate of No. 1 in the same manner as above.

(10) Lamination strength evaluation method
The laminated laminate prepared above was cut into a test piece having a width of 15 mm and a length of 200 mm, and under the conditions of a temperature of 23 ° C. and a relative humidity of 65%, a Tensilon universal material tester (Tensilon UMT-II manufactured by Toyo Baldwin). The laminate strength (normal state) was measured using "-500 type"). For the measurement of the laminate strength, the tensile speed was set to 200 mm / min, and water was applied between the layers of the laminated film layer and the heat-sealing resin layer of each laminated film obtained in Examples and Comparative Examples, and the peeling angle was 90 degrees. The strength when peeled off was measured.
On the other hand, the above-mentioned laminated laminate was subjected to a retort treatment for 30 minutes while being kept in pressurized hot water at a temperature of 120 ° C., and immediately after the retort-treated laminated laminate obtained, the same as above was applied. The test piece was cut out and the laminate strength (after retort treatment) was measured in the same manner as above.

The details of the raw material resin and the coating liquid used in this example and the comparative example are described below. It was used in Examples 1 to 7 and Comparative Examples 1 to 6 and is shown in Tables 1 and 2.
1) Polybutylene terephthalate (PBT): Polybutylene terephthalate used in the film production of the base film layers A-1 to A-11 described later is 1100-211XG (CHANG CHUN PLASTICS CO., LTD., Intrinsic viscosity 1.28 dl. / G) was used.
2) Polyethylene terephthalate (PET): Polyethylene terephthalate used in the production of films for the substrate layers A-1 to A-13, which will be described later, is terephthalic acid // ethylene glycol = 100 // 100 (mol%) (manufactured by Toyobo Co., Ltd.). A viscosity of 0.62 dl / g) was used.

3) Resin having an oxazoline group (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 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): 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 C) was 4 mgKOH / g.

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

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

The method for producing the base film layer used in each Example and Comparative Example is described below. The physical characteristics of the following base film layers A-1 to A-13 and the base film layer B are shown in Tables 1 and 2.
<Base film layer A-1>
Using a uniaxial extruder, 70% by mass of polybutylene terephthalate and 30% by mass of polyethylene terephthalate are mixed, and silica particles with an average particle size of 2.4 μm as inert particles have a silica concentration of 1600 ppm with respect to the mixed resin. After melting the mixture as described above 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, it was rolled 3.8 times in the longitudinal direction (MD) at 60 ° C., then rolled 4.0 times in the transverse direction (TD) at 90 ° C. through a tenter, and subjected to tension heat treatment at 210 ° C. for 3 seconds. After performing a relaxation treatment of 1% for 1 second, the grips at both ends were cut and removed by 10% to obtain a mill roll of a polybutylene terephthalate-based biaxially stretched polyester film having a thickness of 15 μm. Table 1 shows the film forming conditions, physical characteristics and evaluation results of the obtained film.

<Base film layer A-2>
Using a uniaxial extruder, 70% by mass of polybutylene terephthalate and 30% by mass of polyethylene terephthalate are mixed, and silica particles with an average particle size of 2.4 μm as inert particles have a silica concentration of 1600 ppm with respect to the mixed resin. After melting the mixture as described above 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, it was rolled 3.8 times in the longitudinal direction (MD) at 60 ° C., then rolled 4.0 times in the transverse direction (TD) at 90 ° C. through a tenter, and subjected to tension heat treatment at 210 ° C. for 3 seconds. After performing a relaxation treatment of 1% for 1 second, the grips at both ends were cut and removed by 10% to obtain a mill roll of a polybutylene terephthalate-based biaxially stretched polyester film having a thickness of 15 μm. Table 1 shows the film forming conditions, physical characteristics and evaluation results of the obtained film.
In the film forming step of the biaxially stretched film of the base film layer A-1, the resin composition for the coating layer (coating liquid 1) was applied by the fountain bar coating method after MD stretching. Then, it was guided to a tenter while drying, and the solvent was volatilized and dried at a preheating temperature of 70 ° C. Next, under the film-forming conditions shown in Table 1, lateral stretching, heat treatment and relaxation were performed, and one side of a biaxially stretched polyester film (plastic base film layer) having a thickness of 15 μm was coated with 0.020 g / m ² . A two-layer film (plastic base film layer / coating layer) on which a layer was formed was obtained.

<Base film layer A-3>
In the film forming step of the biaxially stretched film of the base film layer A-2, the same procedure as that of the base film layer A-2 was performed except that the relaxation rate in the transverse stretching direction (TD) was changed to 2%.

<Base film layer A-4>
In the film forming step of the biaxially stretched film of the base film layer A-2, the same procedure as that of the base film layer A-2 was carried out except that the heat treatment temperature after the transverse stretching was changed to 205 ° C.

<Base film layer A-5>
In the film forming step of the biaxially stretched film of the base film layer A-2, the same procedure as that of the base film layer A-2 was performed except that the stretching ratio in the vertical direction was changed to 3.3 times.

<Base film layer A-6>
The raw material of the base film layer A-2 was blended with polybutylene terephthalate at 100% by mass and silica particles having an average particle size of 2.4 μm as inert particles so as to have a silica concentration of 1600 ppm with respect to the resin. Except for the above, the same procedure as for the base film layer A-2 was performed.

<Base film layer A-7>
The raw material of the base film layer A-2 is a mixture of 60% by mass of polybutylene terephthalate and 40% by mass of polyethylene terephthalate, and silica particles having an average particle size of 2.4 μm as inert particles are used as silica concentrations with respect to the resin. The procedure was carried out in the same manner as in the base film layer A-2, except that the mixture was blended so as to be 1600 ppm.

<Base film layer A-8>
In the film forming step of the biaxially stretched film of the base film layer A-2, the same procedure as that of the base film layer A-1 was carried out except that the stretching ratio in the vertical direction was changed to 2.5 times.

<Base film layer A-9>
In the film forming step of the biaxially stretched film of the base film layer A-2, the same procedure as that of the base film layer A-2 was performed except that the heat treatment temperature after the transverse stretching was changed to 190 ° C.

<Base film layer A-10>
The raw material of the base film layer A-2 is a mixture of 50% by mass of polybutylene terephthalate resin and 50% by mass of polyethylene terephthalate resin, and silica particles having an average particle size of 2.4 μm as inert particles are used as the silica concentration. The same procedure was used for the base film layer A-2, except that the mixture was blended so as to be 1600 ppm.

<Base film layer A-11>
Manufacture of polyester base film layer and coating of coating liquid 1 (lamination of coating layer)
After pre-crystallization of polyethylene terephthalate, it was finally dried, extruded at 280 ° C. using an extruder having a T-die, and rapidly cooled and solidified on a drum having a surface temperature of 40 ° C. to obtain an amorphous sheet. Next, the obtained sheet was stretched 4.0 times at 100 ° C. in the longitudinal direction between the heating roll and the cooling roll. Then, the coating liquid 1 was coated on one side of the obtained uniaxially stretched film by the fountain bar coating method. Guided to a tenter while drying, preheated at 100 ° C, stretched 4.0 times laterally at 120 ° C, heat treated at 225 ° C with 6% lateral relaxation, biaxially stretched polyester with a thickness of 12 μm. A laminated film having a 0.020 g / m ² coating layer formed on the film was obtained.

<Base film layer B-1>
Manufacture of polyamide base film and coating of coating liquid 1 (lamination of coating layer)
Polycarbonate proamide was heated and melted at 260 ° C. using a screw extruder, extruded into a sheet from a T-die, and then this unstretched sheet was longitudinally stretched 3.3 times at 80 ° C. between a heating roll and a cooling roll. .. Then, the above-mentioned coating liquid 1 was applied to one side of the obtained uniaxially stretched film by the fountain bar coating method. Next, it was guided to a tenter, stretched 4.0 times laterally at 120 ° C., and then heat-fixed at 215 ° C., and a laminated layer in which a 0.020 g / m2 coating layer was formed on a biaxially stretched polyamide film having a thickness of 15 μm. I got a film.

Tables 1 and 2 show the physical properties of the base film layers A-1 to A-11 and the base film layer B-1.
The method of forming the inorganic thin film layer in each Example and Comparative Example is described below.

<Formation of inorganic thin film layer M-1>
As the inorganic thin film layer M-1, a composite oxide layer of silicon dioxide and aluminum oxide was formed on the base film layers A-1 to 13 and the base film layer B by an electron beam vapor deposition method. As the vapor deposition source, particulate SiO ₂ (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) having a purity of about 3 mm to 5 mm were used. The film thickness of the inorganic thin film layer (SiO ₂ / A1 ₂ O ₃ composite oxide layer) in the film (inorganic thin film layer / coating 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.

There are a total of 13 types of the obtained base material laminated film and the laminated laminated body thereof, and the evaluation results thereof are shown in Tables 1 and 2.

According to the present invention, it has excellent barrier properties, rupture resistance, bending resistance, sufficient hand-cutting property in a wet state in the presence of water, and can be used for packaging hard contents such as dry matter packaging. It is possible to provide a laminate that can maintain excellent barrier properties and has less transfer of residual solvent to the contents even when used in applications where severe moist heat treatment such as retort treatment is applied. .. Further, since it can be easily manufactured, it is excellent in both economic efficiency and production stability, and it is possible to provide a gas barrier laminate having uniform characteristics.

Claims (4)

A laminated laminate in which a polyester film, a base material laminated film, and a heat-sealing resin are laminated in this order, and the base material laminated film has an inorganic thin film layer on at least one surface of the base material layer via another layer. It is a laminated film laminated without or without intervention, and the base material layer is a biaxially stretched polyester film base material made of a resin composition containing at least 60% by mass of polybutylene terephthalate, and the following (a). ) And (b) are satisfied at the same time, and the water vapor permeability under 40 ° C. × 90% RH conditions before and after the retort treatment is 1.5 g / m ² · d or less .
(a) The heat shrinkage rate at 150 ° C. in the longitudinal direction and the width direction of the substrate layer is 4.0% or less.
(b) The dimensional change rate at 200 ° C. with respect to the original length of the base material layer of the temperature dimensional change curve measured using TMA (Thermal Mechanical Analyzer) is 0.5 % or less in the longitudinal direction of the base material layer. The laminated laminate according to claim 1, wherein a coating layer is provided between the base material layer and the inorganic thin film layer. The laminated laminate according to claim 1 or 2, wherein the inorganic thin film layer is a layer made of a composite oxide of silicon oxide and aluminum oxide. The laminated laminate according to claim 2 or 3, wherein the coating layer comprises a resin composition containing a resin having an oxazoline group.