JP6819816B2 - Polyester film roll - Google Patents

Description

The present invention relates to a biaxially stretched polyester film used in the packaging field of foods, pharmaceuticals, industrial products, etc., and a method for producing the same. More specifically, it has excellent pinhole resistance and rupture resistance, and even if it is a long film roll with a long winding length, there is little variation in physical properties in the vertical direction (also referred to as the longitudinal direction), and further, the base. Even in the case of producing a gas barrier film by forming an inorganic thin film layer and a protective layer on a wide and long film roll on the material film layer, the streaky wrinkles generated during heat transfer are suppressed and the width is suppressed. The present invention relates to a biaxially stretched polyester film roll capable of making the gas barrier property in the direction (hereinafter, also referred to as the horizontal direction) and the vertical direction uniform.

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 oxidation of proteins and fats and oils, maintain 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, a metal thin film made of aluminum or the like and an inorganic oxide such as silicon oxide or aluminum oxide are used on the surface of a base film layer 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 film layer, pinhole resistance is improved and leakage of contents when the bag is dropped is eliminated (for example, Patent Document 1). 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 its shape is deformed due to shrinkage when 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 (inorganic thin film layer) of an inorganic oxide such as silicon oxide, aluminum oxide, or a mixture thereof is formed is transparent and the contents can be confirmed. Because it is, it is widely used. (For example, Patent Document 2 and Patent Document 3) The PET film has excellent heat resistance and dimensional stability, and can be used even when harsh treatment such as retort sterilization is performed. However, since the PET film is brittle, this can be used. The bag made of the laminated film using the above has the problem that the bag is torn or punctured when dropped, and the contents packed in the bag leak.

As a means for solving these problems, the use of biaxially stretched polybutylene terephthalate (hereinafter abbreviated as PBT) film has been studied. For example, in Patent Document 4, at least PBT resin or a polyester resin composition in which PET resin is blended in a range of 30% by weight or less with respect to PBT resin is 2.7 to 4.0 times simultaneously in the vertical direction and the horizontal direction, respectively. It has been known that a biaxially stretched PBT film obtained by axial stretching is used as a base film layer. According to such a technique, it is possible to obtain a packaging material for liquid filling which has bending pinhole resistance, impact resistance, and excellent aroma retention.

By the way, in the production of a gas barrier film used for food packaging and the like, it is common to process using a wide roll having a width of about 2000 mm. For this reason, if the heat shrinkage characteristics of the film are non-uniform in the lateral direction of the roll, the film will change in size non-uniformly in the lateral direction when the inorganic thin film is processed and when the protective layer is processed thereafter. In some cases, the gas barrier property of the resulting gas barrier film becomes non-uniform. On the other hand, in Patent Document 4 mentioned above, the isotropic property of the film is considered, but the means for improving the dimensional stability in the lateral direction is not considered. Therefore, when an inorganic thin film is formed by using a wide roll of a biaxially stretched PBT film to impart gas barrier properties, it has not been possible to provide a wide film roll that can obtain uniform gas barrier properties in the lateral direction.

Further, in a film made of a polyester resin composition obtained by blending PET resin with PBT resin, it is common to mix PBT resin and PET resin to form a film. However, since the specific gravity and the shape of the resin chip are different between PBT and PET resin, the segregation of these raw material resin chips tends to cause variations in the raw material ratio in the mixing and extrusion steps, resulting in differences in physical properties in the vertical direction of the film. As a result, when a gas barrier film is produced from a long film roll, there is a case where a product having a uniform gas barrier property in the vertical direction cannot be obtained.

Japanese Unexamined Patent Publication No. 2000-25179 Japanese Unexamined Patent Publication No. 6-278240 Japanese Unexamined Patent Publication No. 11-10725 Japanese Unexamined Patent Publication No. 2017-09746

The present invention has been made against the background of the problems of the prior art. That is, it has excellent pinhole resistance and bag breakage resistance, and even if it is a long film roll with a long winding length, there is little variation in physical properties in the vertical direction, and it is wide on the base film layer. Even in the case of producing a gas barrier film by forming an inorganic thin film layer and a protective layer on the roll, biaxially stretched polyester capable of suppressing streaky wrinkles generated during heat transfer and making the gas barrier property in the lateral direction uniform. It is to provide a film and a method for producing the film.

It has excellent pinhole resistance and bag breakage resistance, and is also heat-conveyed even when a wide roll is formed on the base film layer to form an inorganic thin film layer and a protective layer to produce a gas barrier film. In order to suppress the streaky wrinkles that sometimes occur, it is important to make the dimensional change characteristics of the base film in the width direction (also referred to as the lateral direction) uniform. As a result of diligent studies to solve such a problem, the present inventors have reduced the difference in heat shrinkage rate in the lateral direction in the roll of the biaxially stretched PBT film, thereby heating and transporting the wide roll for vapor deposition processing, etc. It was found that the streak-like wrinkles can be suppressed and the gas barrier property in the lateral direction can be made uniform.

Usually, as a method for reducing the heat shrinkage rate in the vertical direction of the polyester film, the stretching ratio when stretching in the vertical direction is lowered, or after stretching in the direction orthogonal to the vertical direction (also referred to as the horizontal direction). A method of increasing the heat-fixing temperature of the film is known, but if an attempt is made to reduce the heat shrinkage rate by using such a method, the thickness accuracy of the film is lowered, the plane orientation is lowered, and the crystal is crystallized. There is a problem that sufficient strength cannot be obtained as a film due to the conversion.

In response to these problems, the present inventors have set a lateral end portion of a polyester film in a step of stretching a polyester unstretched sheet melt-extruded into a sheet in the vertical and horizontal directions, heat-fixing it, heat-relaxing it, and cooling it. It was found that by keeping the temperature of the surface of the film low, the thickness accuracy of the film can be maintained and the difference in heat shrinkage in the lateral direction of the wide film roll can be reduced. This is because the temperature of the surface of the lateral edge of the film is lowered, and the tension applied when winding the film pulls the edge of the film in the vertical direction, so that the heat shrinkage rate of the edge of the film is high. It is thought that this is because it is possible to prevent the temperature from becoming high.

That is, the present invention has the following configuration.
[1] A roll length of 1000 to 1000, which comprises polyester films containing 70% by weight or more of polybutylene terephthalate and simultaneously satisfying the following (1) to (3), and simultaneously satisfying the following (4) to (6). A film roll with a width of 60,000 m and a width of 400 to 3,000 mm.
(1) The puncture strength of the film measured according to JIS Z 1707 is 0.6 N / μm or more.
(2) The degree of surface orientation of the film is 0.144 to 0.165.
(3) The heat shrinkage of the film after heating at 150 ° C. for 15 minutes is 0 to 4% in the vertical direction and -1 to 3% in the horizontal direction.
(4) Sampling from the surface layer of the film roll to the core in the vertical direction every 500 m, the maximum value of the puncture strength measured according to JIS Z 1707 is Xmax (N), the minimum value is Xmin (N), and the average value. The variation in piercing strength represented by the following formula [1 formula] is 20% or less when is set to Xave.
Vertical variation in piercing strength (%) = 100x (Xmax-Xmin) / Xave ... [1 set]
(5) When the maximum value of the puncture strength measured in accordance with JIS Z 1707 measured at a pitch of 100 mm in the lateral direction of the film roll is Ymax (N), the minimum value is Ymin (N), and the average value is Yave. However, the variation in piercing strength represented by the following formula [2 formula] is 20% or less.
Lateral variation in puncture strength (%) = 100x (Ymax-Ymin) / Yave ... [2 formulas]
(6) The difference between the maximum value Zmax (%) and the minimum value Zmin (%) of the heat shrinkage rate in the vertical direction after heating at 150 ° C. for 15 minutes measured at a pitch of 100 mm in the horizontal direction of the film roll is the width of the film roll. The value A (% / m) represented by the following formula [3 formulas] divided is 0.5 or less.
A (% / m) = {Zmax (%) -Zmin (%)} / roll width (m) ... [3 formulas]
[2] The film roll according to [1], wherein the thickness accuracy of the polyester film in both the vertical direction and the horizontal direction is 15% or less.
[3] A laminated film roll in which an inorganic thin film layer is laminated on at least one surface of the film of the film roll according to [1] or [2].
[4] A laminated film roll in which an adhesive layer is laminated on at least one surface of the film of the film roll according to [1] or [2], and an inorganic thin film layer is laminated on the surface of the adhesive layer.
[5] An adhesive layer is laminated on at least one surface of the film of the film roll according to [1] or [2], an inorganic thin film layer is laminated on the surface of the adhesive layer, and a protective layer is provided on the surface of the inorganic thin film layer. Laminated laminated film roll.

By this technique, the present inventors have excellent pinhole resistance and rupture resistance, and even a long film roll having a long winding length has little variation in physical properties in the vertical direction. Even when an inorganic thin film layer and a protective layer are formed on a material film using a wide film roll to produce a gas barrier film, streaky wrinkles generated during heat transfer are suppressed and the width direction (horizontal direction) is suppressed. It has become possible to provide a biaxially stretched polyester film roll capable of making the gas barrier property of (also referred to as) uniform.

FIG. 1 is a schematic view for explaining an example of a method of mixing resin chips for producing the polyester film roll of the present invention.

Hereinafter, the present invention will be described in detail.
The polyester film in the present invention contains PBT as a main component, and the content of PBT is preferably 70% by weight or more, more preferably 75% by weight or more. If it is less than 70% by weight, the piercing strength is lowered, and the film characteristics are not sufficient.
The PBT used as the main constituent component 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, as a dicarboxylic acid component. %. 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 the diol.

The polyester film in the present invention may contain a polyester resin other than PBT for the purpose of adjusting mechanical properties and the like.
As the polyester resin other than PBT, at least one polyester resin 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 resin, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, neopentyl glycol in which at least one dicarboxylic acid selected from the group consisting of acid, adipic acid, azelaic acid and sebacic acid is copolymerized. , 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, polyethylene glycol, polytetramethylene glycol, PBT resin in which at least one diol component selected from the group consisting of polycarbonate diol is copolymerized, etc. Can be mentioned.

The upper limit of the amount of the polyester resin other than the PBT resin added is preferably less than 30% by weight, more preferably 25% by weight or less. If the amount of polyester resin other than PBT resin added exceeds 30% by weight, the mechanical properties of PBT are impaired, impact strength, pinhole resistance, or bag breakage resistance becomes insufficient, as well as transparency and gas barrier. Sexual deterioration may occur.

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 piercing strength, impact strength, pinhole resistance, bag breaking resistance, etc. May decrease.
The upper limit of the intrinsic viscosity of the PBT resin is preferably 1.4 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, but 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 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, and even 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, and even more preferably 1800 ppm. If it exceeds the above, transparency may decrease.

The lower limit of the thickness of the polyester film in the present invention 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 thickness of the polyester film in the present invention 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 lower limit of the piercing strength (hereinafter, may be abbreviated as piercing strength) of the polyester film measured according to JIS Z 1707 in the present invention is preferably 0.6 N / μm. If it is 0.6 N / μm or more, the strength of the bag may be insufficient when it is used as a bag.

The lower limit of the plane orientation (ΔP) of the polyester film in the present invention is preferably 0.144, more preferably 0.148, and even more preferably 0.15. If it is less than the above, the orientation is weak and sufficient strength may not be obtained, which may reduce the bag-breaking resistance, or an inorganic thin film layer and a protective layer are provided on the base film layer to form a laminated film. In some cases, the tension and temperature applied when the protective film is formed make it easy to stretch, and the inorganic thin film layer is cracked, so that the gas barrier property may be lowered.
The upper limit of the plane orientation (ΔP) of the polyester film in the present invention is preferably 0.165, more preferably 0.158. If it exceeds the above, the orientation becomes too strong and it becomes easy to break during film formation. Further, as the orientation is increased, heat fixation at a high temperature is required to reduce the heat shrinkage rate, and crystallization may rather reduce the strength of the film.

The upper limit of the heat shrinkage rate after heating the polyester film in the longitudinal direction at 150 ° C. for 15 minutes in the present invention is preferably 4.0%, more preferably 3.0%, still more preferably 2%. .. If the upper limit is exceeded, the inorganic thin film layer may crack due to the dimensional change of the base film layer 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 upper limit of the heat shrinkage rate after heating the polyester film in the lateral direction at 150 ° C. for 15 minutes in the present invention is preferably 3.0%, more preferably 2.0%, and even more preferably 1%. If the upper limit is exceeded, the inorganic thin film layer may crack due to the dimensional change of the base film layer 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 lateral dimensional changes during processing.

The lower limit of the heat shrinkage rate after heating the polyester film in the longitudinal direction at 150 ° C. for 15 minutes in the present invention is preferably 0%. Even if it is less than the above, the effect of improvement cannot be obtained any more (saturation), and it may become mechanically brittle.
The lower limit of the heat shrinkage rate after heating the polyester film in the lateral direction at 150 ° C. for 15 minutes in the present invention is preferably 1.0%. Even if it is less than the above, the effect of improvement cannot be obtained any more (saturation), and it may become mechanically brittle.

The upper limit of the thickness accuracy of the polyester film in the vertical direction and the horizontal direction in the present invention is preferably 15% or less, more preferably 12% or less, and most preferably 10% or less.
If the thickness accuracy of the film is 15% or more, not only the appearance of the obtained film roll is deteriorated, but also wrinkles are generated when the gas barrier layer and the protective layer are formed later, and winding deviation due to meandering may occur. is there.

The lower limit of the impact strength of the polyester film 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 base film layer in the present invention is preferably 0.2 J / μm. If it is 0.2 J / μm, the effect of improvement may be sufficient.

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

The roll width of the polyester film roll of the present invention is preferably 400 mm or more, more preferably 1000 mm or more, and further preferably 1500 mm or more, from the viewpoint of improving productivity in the secondary processing step.
A gas barrier film roll can be produced more economically by performing a process for imparting gas barrier property by using a film roll having a wider width and a longer length.

In the polyester film roll of the present invention, the film roll is sampled in the vertical direction from the surface layer of the film roll to the winding core every 500 m, and the maximum value of the puncture strength measured according to JIS Z 1707 is Xmax (N) and the minimum value is Xmin. (N), when the average value is Xave, the variation in the puncture strength represented by the following formula [1 formula] is preferably 20% or less, more preferably 15% or less, and most preferably 10% or less. Is.
Vertical variation in puncture strength (%) = 100x (Xmax-Xmin) / Xave ... [1 set]
If the variation in the vertical puncture strength of the film roll exceeds 20%, the quality of the packaging bag manufactured by secondary processing of the polyester film may vary.

In the polyester film roll of the present invention, the film roll is sampled in the lateral direction at a pitch of 100 mm, and the maximum value of the puncture strength measured according to JIS Z 1707 is Ymax (N), the minimum value is Ymin (N), and the average value is Yave. The variation in puncture strength represented by the following formula [2 formula] is preferably 20% or less, more preferably 15% or less, and most preferably 10% or less.
Lateral variation in puncture strength (%) = 100x (Ymax-Ymin) / Yave ... [2 formulas]
If the variation in the lateral puncture strength of the film roll exceeds 20%, the quality of the packaging bag manufactured by secondary processing of the polyester film may vary.

The polyester film roll of the present invention has a value Y (% /% /% /) obtained by dividing the difference between the maximum and minimum heat shrinkage after heating at 150 ° C. in the vertical direction at a pitch of 100 mm in the horizontal direction for 15 minutes by the width of the roll. m) is preferably 0.5 or less.
Y (% / m) = {maximum heat shrinkage (%) -minimum heat shrinkage (%)} / roll width (m) ... [7 formulas]
When the value Y obtained by dividing the difference between the maximum and minimum vertical heat shrinkage measured at a pitch of 100 mm in the lateral direction by the width of the roll is greater than 0.5% / m, the film is inorganic to the film using a wide roll. In the case of producing a gas barrier film by forming a thin film layer or a protective layer, it is not possible to suppress streak-like wrinkles generated during heat transfer, and the gas barrier property may become non-uniform in the lateral direction. is there.

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

Next, a manufacturing method for obtaining the polyester film roll of the present invention will be specifically described. It is not limited to these.
In order to obtain the polyester film roll of the present invention, a polybutylene terephthalate resin chip and another raw material resin chip are supplied and mixed in an extruder equipped with a hopper, and the polyester raw material resin is formed into a sheet from the extruder. A step of melt-extruding and cooling on a casting drum to form an unstretched sheet, a longitudinal stretching step of stretching the molded unstretched sheet in the longitudinal direction, and a preheating step of preheating to a temperature at which lateral stretching is possible after the longitudinal stretching. , A transverse stretching step of stretching in a width direction (also referred to as a transverse direction) orthogonal to the longitudinal direction, a heat fixing step of heating and crystallizing the film after the longitudinal stretching and the transverse stretching, and the heat-fixed film. It consists of a heat relaxation step for removing the residual strain of the resin and a cooling step for cooling the film after the heat relaxation.

[Unstretched sheet molding process]
First, the film raw material is 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.

When mixing the resin chips as the raw material, the polybutylene terephthalate resin chips are supplied to the hopper from above, and the pipe (hereinafter, may be referred to as an inner pipe) having an outlet in the hopper and directly above the extruder is used. It is preferable to supply resin chips other than PBT, mix both chips, and melt-extrude them. If PBT resin chips and other resin chips are mixed and placed in a hopper on an extruder, resin chips with different specific gravity and chip shape may cause segregation of raw materials in the hopper, especially the inner wall of the hopper. There is a high concern that raw material segregation will occur in non-vertical areas (oblique areas), but if a resin other than polybutylene terephthalate resin chip is directly supplied to the upper part of the extruder in the hopper through the inner pipe, the specific gravity and chip Even if the shapes are different, the bias of raw materials can be reduced, and polyester film rolls can be stably industrially produced.

An example of a specific mixing procedure is shown in FIG. FIG. 1 is a schematic view showing an example of the relationship between the extruder 2 provided with the hopper 1 and the inner pipe 3. As shown in FIG. 1, resins other than the polybutylene terephthalate resin chip, which is the main raw material of the polyester film of the present invention, are supplied through the inner pipe 3, and the polybutylene terephthalate resin chip is supplied from the upper part of the hopper 1. Since the outlet 4 of the inner pipe 3 is directly above the extruder (to be exact, directly above the resin supply port 5 of the extruder 2), the mixing ratio of the raw materials can be kept constant.

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 the molten polyester resin is cast on an extruded cooling roll, it is preferable to reduce the difference in crystallinity in the lateral 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. Since the PBT resin has a high crystallization rate, 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 capable of suppressing 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.

The method of extruding a molten polyester resin and casting by stacking raw materials having the same composition in multiple layers when casting is specifically a step of melting a resin composition containing 70% by weight or more of PBT resin to form 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. Other steps may be inserted between the steps (1) and the steps (2), and between the steps (2) and the steps (3). For example, a filtration step, a temperature changing step, or the like may be inserted between the steps (1) and (2). Further, a temperature changing step, a charge adding step, and the like may be inserted between the steps (2) and the steps (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 lateral direction of the sheet, those having a rectangular melt line are more preferable. It is further preferred to use a static mixer with a rectangular melt line or a multi-layer feed block. The resin composition composed of a plurality of layers formed by merging the plurality of resin compositions may be passed through any one or more of the static mixer, the multilayer feed block, and the 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 if the distance between the layer interfaces becomes too long, the crystal size becomes too large, and the effect of the present invention tends not to be obtained. 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. 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 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 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 multilayer 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 step (3), the laminated fluid is discharged from the die and brought into contact with the cooling roll to solidify. 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 lateral direction of the surface of the cooling roll. At this time, the thickness of the unstretched sheet is preferably in the range of 15 to 2500 μm. The multi-layered unstretched sheet 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.

[Vertical stretching and transverse stretching steps] 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 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 horizontal 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 puncture 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.

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 and 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. If it is 5.0 times or less, the effect of improving the mechanical strength and thickness unevenness is maximized (saturated) even in this range.

[Heat fixing process]
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 section process]
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 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 step exceeds 80 ° C., the edge is stretched by the tension applied when the film is wound, 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 (also referred to as the lateral direction) of the roll becomes non-uniform, and when such a roll is heated and conveyed for vapor deposition processing or the like, streaky wrinkles occur. The physical properties of the finally obtained gas barrier film may become non-uniform in the lateral direction. Further, by setting the film end portion to 80 ° C. or lower in the step, it is possible to suppress an increase in the heat shrinkage rate of the end portion without lowering the stretching ratio in the vertical direction or raising the heat fixing temperature. , It is possible to suppress deterioration of film thickness accuracy and physical strength.

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 of the cooling step, a shielding plate is provided on the central side in the lateral 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.

[Inorganic thin film layer]
In the present invention, the gas barrier property can be imparted by providing the inorganic thin film layer on the surface of the biaxially stretched polyester film.
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 made 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 weight of Al in terms of the weight ratio of the metal content. If the Al concentration is less than 20% by weight, the water vapor barrier property may be lowered. On the other hand, if it exceeds 70% by weight, 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. The silicon oxide referred to here is various silicon oxides such as SiO and SiO ₂ or a mixture thereof, and 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. 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 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 particle diameter 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-deposited body, heating / cooling, and the like can be similarly changed when the sputtering method or the CVD method is adopted.

[Adhesive layer]
In the gas via laminating film of the present invention, an adhesive layer can be provided between the base film layer and the inorganic thin film layer for the purpose of ensuring the gas barrier property and the laminating strength after the retort treatment. The resin composition used for the adhesive layer provided between the base film layer and the inorganic thin film layer includes urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, polybutadiene-based resins, and epoxy. Examples thereof include those to which a curing agent such as a system, an isocyanate system, or a melamine system is added. The resin composition used for these adhesive 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 laminate strength after the retort treatment is further improved.

Among the resin compositions used for the adhesive layer, it is preferable to use a mixture of a resin containing an oxazoline group, an acrylic resin and a urethane resin. The oxazoline group has a high affinity with the inorganic thin film, and can react with the oxygen-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 existing in the adhesive layer can react with the carboxylic acid terminal generated by hydrolysis of the base film layer and the adhesive layer to form a crosslink.

The method for forming the adhesive 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 in-line 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 film 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, 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. Examples of the solvent (solvent) used when the coating method is used include aromatic solvents such as benzene and toluene; alcohol solvents such as methanol and ethanol; ketone solvents such as acetone and methyl ethyl ketone; ethyl acetate and butyl acetate. Etc., and examples thereof include polyhydric alcohol derivatives such as ethylene glycol monomethyl ether.

[Protective layer]
In the present invention, a protective layer is provided on the inorganic thin film layer. The metal oxide layer is not a completely dense film, but is dotted with minute defects. 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 laminated film is greatly improved.

The resin composition used for the protective layer formed on the surface of the inorganic thin film layer of the laminated film in the present invention includes resins such as urethane-based, polyester-based, acrylic-based, titanium-based, isocyanate-based, imine-based, and polybutadiene-based resins, and epoxy. Examples thereof include those to which a curing agent such as a system, an isocyanate system, or a melamine system is added. In the 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 the amorphous portion, so that damage to the inorganic thin film layer is suppressed even when a bending load is applied. It is preferable because it can be used. 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 coat appearance 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 an aromatic or aromatic aliphatic diisocyanate component as a main 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, good gas barrier properties can be obtained.

In the present invention, the proportion of aromatic or aromatic aliphatic diisocyanate in the urethane resin is preferably in the range of 50 mol% or more (50 to 100 mol%) in 100 mol% of the polyisocyanate component (F). The ratio of the total amount of the aromatic or 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 proportion of the total amount of aromatic or aromatic aliphatic diisocyanates 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-methylmorpholin and N-ethylmorpholin. 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. 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 glycol. Examples thereof include polyhydric alcohol derivatives such as monomethyl ether.

From the above, the polyester film of the present invention is excellent in bag-breaking resistance and bending resistance, and a wide roll is formed on the base film layer to form an inorganic thin film layer and a protective layer to produce a gas barrier film. Even in such a case, it is possible to suppress streak-like wrinkles generated during heat transfer and make the gas barrier property in the lateral direction uniform.

[Packaging material]
When the film roll of the present invention is used as a packaging material, it is preferable to form a thermosetting resin layer called a sealant. The heat-sealing resin layer is usually provided on the inorganic thin film layer, but may be provided on the outside of the base film layer (the surface opposite to the adhesive layer forming surface). 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. , Polyethylene-α-olefin random copolymer, ionomer resin and the like can be used.

Further, the film roll of the present invention has at least one or more printing layer or other plastic base material and / or paper base material between or outside the inorganic thin film layer or the base film layer and the thermosetting resin layer. It may be laminated.

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 acrylic resin, urethane resin, polyester resin, vinyl chloride resin, 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.

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.

[Film thickness]
It was measured using a dial gauge in accordance with JIS K7130-199 A method.

[Film vertical thickness accuracy]
A piece of film is cut out in the vertical direction from the center of the obtained film roll, and the maximum thickness when measured at 100 points with a dial gauge at a pitch of 5 cm is Tmax, the minimum thickness is Tmin, and the average thickness is Tave. The thickness accuracy (Tv) was obtained from [Equation 4] of.
Vertical direction Tv (%) = {(Tmax-Tmin) / Tave} x 100 (%) ... [4 formulas]
[Film lateral thickness accuracy]
The obtained film roll having a width of 1000 mm was cut out in the horizontal direction, and the maximum thickness was Tmax, the minimum thickness was Tmin, and the average thickness was Tave when measured at 20 points with a dial gauge at a pitch of 5 cm. The thickness accuracy (Tv) was obtained from the formula].
Lateral Tv (%) = {(Tmax-Tmin) / Tave} x 100 (%) ... [5 formulas]

[Film surface orientation ΔP]
About the sample The refractive index (Nx) in the vertical direction and the refractive index (Ny) in the horizontal direction of the film were measured by the Abbe refractometer using the sodium D line as the light source by the JIS K 7142-1996 A method, and from the following [Equation 6]. The plane orientation ΔP was calculated.
Planar orientation (ΔP) = (Nx + Ny) /2-Nz ... [Equation 6]

[Heat shrinkage of 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).

[Width direction (horizontal) uniformity of heat shrinkage rate]
The obtained film roll was sampled at a pitch of 100 mm in the horizontal direction of the roll, and the heat shrinkage rate in the vertical direction was measured according to the method described above. From the maximum and minimum values of the obtained heat shrinkage and the width of the film roll, Y (% / m) was obtained from the following [Equation 7].
Y (% / m) = {maximum heat shrinkage (%) -minimum heat shrinkage (%)} / roll width (m) ... [7 formulas]

[Film piercing strength]
The obtained polyester film was sampled into a 5 cm square, and made into JIS Z1707 using the digital force gauge "ZTS-500N" manufactured by Imada Co., Ltd., the electric measuring stand "MX2-500N", and the piercing jig "TKS-250N". The puncture strength of the film was measured accordingly. The unit is N / μm.

[Variation of puncture strength in the longitudinal direction (longitudinal direction)]
The obtained polyester film roll (width 2080 mm, winding length 30,000 m) was sampled in the vertical direction from the surface layer of the film roll to the winding core every 500 m. The puncture strength of each sampled film was measured according to JIS Z 1707.
The maximum value of the obtained piercing strength was Xmax (N), the minimum value was Xmin (N), and the average value was Xave, and the variation in piercing strength represented by the following [1 equation] was determined.
Vertical variation in puncture strength (%) = 100x (Xmax-Xmin) / Xave ... [1 set]

[Variation of puncture strength in the width direction (horizontal direction)]
A polyester film roll similar to the above was sampled laterally every 100 mm. The puncture strength of each sampled film was measured according to JIS Z 1707.
The maximum value of the obtained piercing strength was Ymax (N), the minimum value was Ymin (N), and the average value was Yave, and the variation in piercing strength represented by the following [2 equation] was obtained.
Lateral variation in puncture strength (%) = 100x (Ymax-Ymin) / Yave ... [2 formulas]

[Impact strength of film]
Using an impact tester manufactured by Toyo Seiki Seisakusho Co., Ltd., the strength of the film against impact punching in an atmosphere of 23 ° C. was measured. The impact spherical surface used was one with a diameter of 1/2 inch. The unit is J / μm.

The details of the raw material resin used in this example and the comparative example and the coating liquid used for the adhesive layer and the protective layer are described below. The composition of the raw material resin used is shown in Tables 1 to 4.
1) PBT resin: As the polybutylene terephthalate resin used in the production of the biaxially stretched polyester film described later, 1100-211XG (CHANGE CHUN PLASTICS CO., LTD., Intrinsic viscosity 1.28 dl / g) was used.
2) PET resin: The PET resin used in the production of the biaxially stretched polyester film described later is terephthalic acid // ethylene glycol = 100 // 100 (mol%) (manufactured by Toyobo Co., Ltd., intrinsic viscosity 0.62 dl / g). There was.

3) Resin having an oxazoline group (B): 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%) is prepared. did. The amount of oxazoline groups in this resin was 7.7 mmol / g.

4) Acrylic resin (C)]: As an acrylic resin, a 25% by weight emulsion of a commercially available acrylic acid ester copolymer (“Mobile (registered trademark) 7980” manufactured by Nichigo Vinyl Co., Ltd.” was prepared. This acrylic resin (B). The acid value (theoretical value) of) was 4 mgKOH / g.

5) Urethane resin (D): 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) Urethane resin (E) ;: As a 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 or aromatic aliphatic diisocyanate to the total polyisocyanate component measured by 1H-NMR was 85 mol%.

7) Coating liquid used for the adhesive layer 1
Each material was mixed at the following blending ratio to prepare a coating liquid (resin composition for an adhesive layer).
Water 54.4% by weight
Isopropanol 25.0% by weight
Oxazoline group-containing resin (A) 15.0% by weight
Acrylic resin (B) 3.6% by weight
Urethane resin (C) 2.0% by weight

8) Coating liquid used for coating the protective layer 2
The following coating agents were mixed to prepare a coating liquid 2. Here, the weight ratio of the urethane resin (E) in terms of solid content is as shown below.
Water 60.0% by weight
Isopropanol 30.0% by weight
Urethane resin (E) 10.0% by weight

[Preparation of Laminated Film] Shown in Examples 1-1 to 1-8, Examples 2-1 to 2-8, Comparative Examples 1-1 to 1-5 and Comparative Examples 2-1 to 2-5, which will be described later. Urethane-based two-component curable adhesive (Mitsui Chemicals, Inc. "Takelac (registered trademark) A525S" and "Takenate (registered trademark) A50" 13.5: 1 (weight ratio) on the protective layer side of the gas barrier film A 70 μm-thick unstretched polypropylene film (“P1147” manufactured by Toyo Boseki Co., Ltd.) is attached as a thermosetting resin layer by a dry laminating method, and aged at 40 ° C. for 4 days. To obtain a laminate for evaluation. The thickness of the adhesive layer formed of the urethane-based two-component curable adhesive after drying was about 4 μm.

[Water Vapor Permeability of Laminated Film] With respect to the above-mentioned laminated laminate, a water vapor permeability measuring device (“PERMATRAN-W1A” manufactured by MOCON) was used in accordance with the JIS-K7129-1992 B method, and the temperature was 40 ° C. The water vapor permeability under normal conditions was measured in an atmosphere with a humidity of 90 RH%. The water vapor permeability was measured in the direction in which water vapor permeated from the base film layer side to the sealant side.

[Water Vapor Transmittance After Retort of Laminated Film] The above-mentioned laminated film was subjected to a wet heat treatment for 30 minutes in hot water at 130 ° C. and dried at 40 ° C. for 1 day (24 hours) to obtain the obtained product. The water vapor permeability of the laminated film after the moist heat treatment was measured in the same manner as above.

The method for producing the biaxially stretched polyester film used in each Example and Comparative Example is described below. The physical characteristics of the following biaxially stretched polyester film are shown in Tables 1 to 4.

<Example 1-1> Using a uniaxial extruder, 20% by weight of PET resin mixed with 80% by weight of PBT resin and silica particles having an average particle size of 2.4 μm as inert particles so as to be 7000 ppm is blended. Was melted at 290 ° C., and then the melt line was introduced into a 12-element static mixer. However, the PET resin was put in using an inner pipe as shown in FIG. 1 so as to be mixed with other raw materials before entering the extruder. The polyester resin melt was divided and laminated by a static mixer 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 2.9 times in the longitudinal direction at 60 ° C., then passed through a tenter and stretched 4.0 times in the lateral direction at 90 ° C., tension heat treatment at 200 ° C. for 3 seconds and relaxation of 9% for 1 second. After the treatment was carried out, the film was cooled by cooling at 50 ° C. for 2 seconds. The surface temperature of the edge of the film at this time was 75 ° C. Next, the grips at both ends were cut and removed by 10% to obtain a roll of the full width of the polyester film having a thickness of 15 μm and a total width of 4200 mm (hereinafter referred to as a mill roll). The obtained mill roll was slit, and two slit rolls having a roll width of 2080 mm were collected to form an inorganic thin film layer and further to form a protective layer 1. The results of evaluating the obtained film rolls and laminated film rolls are shown in Table 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> As the inorganic thin film layer, a composite oxide layer of silicon dioxide and aluminum oxide was formed 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 laminate film (inorganic thin layer / adhesive layer / polyamide 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 (weight ratio) = 60/40.

<Formation of Protective Layer 1 on Vapor Deposited Film> The coating liquid 2 was applied onto the inorganic thin film layer deposited and formed above by the 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 (as Dry solid content). As described above, a laminated film having an adhesive layer / metal oxide layer / protective layer on the base film layer was produced. Table 1 shows the film forming conditions, physical characteristics and evaluation results of the obtained film.

<Examples 1-2 to 1-8, Comparative Examples 1-1 to 1-5> In the film forming process of the biaxially stretched polyester films 2 to 8 and 1 to 5 of the biaxially stretched polyester films, the ratio of the PBT resin, The same procedure as in Example 1-1 was carried out except that the extrusion temperature, the longitudinal and horizontal stretching ratio, the relaxation rate and the cooling step zone temperature were shown in Tables 1 and 2.

<Example 2-1> Using a uniaxial extruder, a mixture of 80% by weight of PBT resin and 20% by weight of PET resin is mixed with silica particles having an average particle size of 2.4 μm as inert particles as the silica concentration. After melting the mixture at 290 ° C., the melt line was introduced into a 12-element static mixer. As a result, the polyester resin 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 resin composition for the adhesive layer (coating liquid 1) was applied by the fountain bar coating method after the vertical stretching at 60 ° C. for 2.9 times roll stretching. Then, it is guided to a tenter while drying, then passed through a tenter and stretched 4.0 times in the lateral direction at 90 ° C., subjected to tension heat treatment at 200 ° C. for 3 seconds and relaxation treatment of 9% for 1 second, and then 50. The film was cooled by cooling at ° C. for 2 seconds. The surface temperature of the edge of the film at this time was 75 ° C. Next, the grips at both ends were cut and removed by 10% to obtain a mill roll of a polyester film having a thickness of 15 μm and a total width of 4200 mm. The obtained mill roll was slit, and two slit rolls having a width of 2080 mm were collected. Table 3 shows the film forming conditions, physical characteristics and evaluation results of the obtained film.

<Comparative Example 1-6> Using a uniaxial extruder, 20% by weight of PET resin mixed with 80% by weight of PBT resin and silica particles having an average particle size of 2.4 μm as inert particles so as to be 7000 ppm is blended. Was melted at 290 ° C., and then the melt line was introduced into a 12-element static mixer. The inner pipe was not used for mixing the PBT resin and the PET resin, and the PBT resin and the PET resin were mixed at the upper part of the hopper. The polyester resin melt was divided and laminated by a static mixer 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 2.9 times in the longitudinal direction at 60 ° C., then passed through a tenter and stretched 4.0 times in the lateral direction at 90 ° C., tension heat treatment at 200 ° C. for 3 seconds and relaxation of 9% for 1 second. After the treatment was carried out, the film was cooled by cooling at 50 ° C. for 2 seconds. The surface temperature of the edge of the film at this time was 75 ° C. Next, the grips at both ends were cut and removed by 10% to obtain a roll of the full width of the polyester film having a thickness of 15 μm and a total width of 4200 mm (hereinafter referred to as a mill roll). The obtained mill roll was slit, and two slit rolls having a roll width of 2080 mm were collected. Table 2 shows the film forming conditions and the evaluation results of the obtained film roll and laminated film roll.

<Examples 2-2 to 2-8, Comparative Examples 2-1 to 2-5> Film formation of biaxially stretched polyester films 2-1 to 2-8 and 2-1 to 2-5. In the step, the same procedure as in Example 2-1 was carried out except that the ratio of PBT, the extrusion temperature, the vertical and horizontal stretching ratio, the relaxation rate and the cooling step zone temperature were shown in Tables 3 and 4. The evaluation results of the obtained film rolls and laminated film rolls are shown in Tables 3 and 4.

As shown in Tables 1 to 4, the difference in heat shrinkage in the width (horizontal) direction of the polyester film roll can be reduced by setting the surface temperature of the film edge at the tenter outlet to 80 ° C. or lower. A film roll having a small difference in physical properties in the width direction could be obtained.

Further, as can be seen from the comparison between Comparative Examples 1-6 and Examples, by using the inner pipe for supplying the raw material, the variation in the puncture strength in the vertical direction could be reduced.

Further, as seen in Examples 1-1 to 1-8, by cooling the temperature of the film end at the tenter outlet to 80 ° C. or lower, the heat shrinkage of the obtained mill roll end can be determined. This can be suppressed, and the difference in heat shrinkage rate in the vertical direction of the slit roll can be reduced. As a result, the generation of streaky wrinkles was suppressed when the inorganic thin film layer and the protective layer were formed, and the gas barrier property in the lateral direction was made uniform. Further, as seen in Examples 2-1 to 2-8, by having an adhesive layer between the base film layer and the inorganic thin film layer, a harsh wet heat treatment such as a retort sterilization treatment is further performed. Even after that, it was possible to maintain a high gas barrier property.

In Comparative Example 1-1 and Comparative Example 2-1, since the heat fixing temperature is raised to suppress the heat shrinkage in the vertical direction, the film is largely distorted in the horizontal direction, and the heat shrinkage at the edges is large. As a result, the gas barrier property at the end is inferior. In addition, the variation in puncture strength in the lateral direction was large. Similar to the above, Comparative Example 1-2 and Comparative Example 2-2 have a large difference in heat shrinkage between the central portion and the end portion of the mill roll, and not only the gas barrier property at the end portion is inferior, but also the ratio of PBT is small, which is sufficient. The piercing strength is not obtained. In Comparative Example 1-3 and Comparative Example 2-3, and Comparative Example 1-4 and Comparative Example 2-4, the puncture strength is improved by increasing the draw ratio and the degree of surface orientation, but Comparative Example 1- Similar to 1 and Comparative Example 2-1 the heat shrinkage rate of the end portion is high, and the uniformity of the gas barrier property in the lateral direction becomes insufficient. In Comparative Examples 1-5 and 2-5, as a result of raising the heat fixing temperature in order to suppress the heat shrinkage in the vertical direction, the heat shrinkage at the central portion is small, but the difference from the end portion is large. , The gas barrier property was non-uniform in the lateral direction. In addition, the mechanical strength of the film was reduced.

In Comparative Examples 1-6, since the inner pipe was not used for supplying the raw materials and the raw material ratio fluctuated greatly in the vertical direction due to the segregation of the raw materials, the variation in the puncture strength in the vertical direction was large.

According to the present invention, a gas barrier film is produced by forming an inorganic thin film layer and a protective layer on a base film layer using a wide film roll while having excellent pinhole resistance and bag breakage resistance. Even in such a case, it has become possible to provide a biaxially stretched polyester film roll capable of suppressing wrinkles generated during heat transfer and making the gas barrier property in the lateral direction uniform. Since it can be widely applied as a food packaging material, it is expected to greatly contribute to the industrial world. By using the polyester film roll of the present invention, a gas barrier film roll having uniform gas barrier properties in the vertical and horizontal directions can be economically obtained, and therefore, it can be used for food packaging, pharmaceuticals, industrial products, and the like. it can. Further, it can be widely used in industrial applications such as solar cells, electronic paper, organic EL elements, and semiconductor elements.

1 Hopper 2 Extruder 3 Inner pipe 4 Inner pipe outlet 5 Raw material resin supply port

Claims (5)

A roll length of 1000 to 60,000 m, which comprises a polyester film containing 70% by weight or more of polybutylene terephthalate and simultaneously satisfying the following (1) to (3), and simultaneously satisfying the following (4) to (6). , A film roll with a width of 400 to 3,000 mm.
(1) The puncture strength of the film measured according to JIS Z 1707 is 0.6 N / μm or more.
(2) The degree of surface orientation of the film is 0.144 to 0.165.
(3) The heat shrinkage of the film after heating at 150 ° C. for 15 minutes is 0 to 4% in the vertical direction and -1 to 3% in the horizontal direction.
(4) The maximum value of the puncture strength measured in the vertical direction from the surface layer of the film roll to the winding core every 500 m and measured according to JIS Z 1707 is Xmax (N), the minimum value is Xmin (N), and the average value. The variation in piercing strength represented by the following formula [1 formula] is 20% or less when is set to Xave.
Vertical variation in piercing strength (%) = 100x (Xmax-Xmin) / Xave ... [1 set]
(5) When the maximum value of the puncture strength measured according to JIS Z 1707 measured at a pitch of 100 mm in the lateral direction of the film roll is Ymax (N), the minimum value is Ymin (N), and the average value is Yave. However, the variation in piercing strength represented by the following formula [2 formula] is 20% or less.
Lateral variation in puncture strength (%) = 100x (Ymax-Ymin) / Yave ... [2 formulas]
(6) The difference between the maximum value Zmax (%) and the minimum value Zmin (%) of the heat shrinkage rate in the vertical direction after heating at 150 ° C. for 15 minutes measured at a pitch of 100 mm in the horizontal direction of the film roll is the width of the film roll. The value A (% / m) represented by the following formula [3 formulas] divided is 0.5 or less.
A (% / m) = {Zmax (%) -Zmin (%)} / roll width (m) ... [3 formulas] The film roll according to claim 1, wherein the thickness accuracy of the polyester film in both the vertical direction and the horizontal direction is 15% or less. A laminated film roll in which an inorganic thin film layer is laminated on at least one surface of the film of the film roll according to claim 1 or 2. A laminated film roll in which an adhesive layer is laminated on at least one surface of the film of the film roll according to claim 1 or 2, and an inorganic thin film layer is laminated on the surface of the adhesive layer. A laminated film in which an adhesive layer is laminated on at least one surface of the film of the film roll according to claim 1 or 2, an inorganic thin film layer is laminated on the surface of the adhesive layer, and a protective layer is laminated on the surface of the inorganic thin film layer. roll.