JP6642748B2 - Laminated film - Google Patents

Description

  The present invention relates to a laminated film using a polyester resin recycled from a PET bottle. More specifically, when a polyester resin recycled from a PET bottle is used, and a low heat shrinkage property and a small thickness unevenness are used to form a gas barrier laminate film having an inorganic thin film layer and a sealant layer, the laminate exhibits good gas barrier properties. About the film.

  Conventionally, there has been known a technology of using a polyester resin recycled from a PET bottle to produce a polyester film for a body-wound label from a polyester having a low oligomer content and having little trouble due to static electricity without impairing productivity and quality. (For example, see Patent Document 1). However, such a conventional technique uses a raw resin (IV = 0.70 dl / g) having a high intrinsic viscosity and extrudes at a low extrusion temperature (280 ° C.), so that the composition inside the film varies, and the variation of the laminate surface varies. This results in poor generation and uneven thickness. In addition, in order to obtain high lamination strength, the film after biaxial stretching is heat-treated at a high temperature.However, since the film is rapidly cooled to room temperature, the relaxation of the film varies in the plane, and the thickness unevenness is poor. Become. Therefore, when an inorganic thin film is deposited on such a polyester film having a large thickness unevenness as a base material, there is a problem that the thickness of the inorganic thin film is not uniform, and the gas barrier property is reduced.

  Further, a technique has been known in which a polyester film for transparent vapor deposition suitable for adhesion between a thin film and a polyester film and for boil and retort treatments is obtained by controlling the orientation of the film (for example, see Patent Document 2). However, such a prior art is an example of polyethylene terephthalate that does not use a polyester resin recycled from a PET bottle. However, when a film is formed using a resin material having an intrinsic viscosity of 0.63 dl / g made of the same recycled resin. Since there are variations in the composition inside the film, variations in the laminate surface occur and defects in thickness unevenness occur. In addition, in order to obtain high lamination strength, the film after biaxial stretching is heat-treated at a high temperature.However, since the film is rapidly cooled to room temperature, the relaxation of the film varies in the plane, and the thickness unevenness is poor. Become. Therefore, when an inorganic thin film is deposited on such a polyester film having a large thickness unevenness as a base material, there is a problem that the thickness of the inorganic thin film layer is not uniform and the gas barrier property is reduced.

  Further, there has been known a technique of controlling the particles in a film and film forming conditions to improve the slitting property and the shaving property in a calendering step for a magnetic recording medium (for example, see Patent Document 3). However, such a prior art is an example of polyethylene terephthalate that does not use a polyester resin recycled from a PET bottle. However, when a film is formed using a resin material having an intrinsic viscosity of 0.62 dl / g made of the same recycled resin. In this case, since the composition inside the film varies, the variation in the laminated surface and the unevenness in the thickness become poor. In addition, in order to obtain high lamination strength, the film after biaxial stretching is heat-treated at a high temperature.However, since the film is rapidly cooled to room temperature, the relaxation of the film varies in the plane, and the thickness unevenness is poor. Become. Therefore, when an inorganic thin film is deposited on such a polyester film having a large thickness unevenness as a base material, there is a problem that the thickness of the inorganic thin film layer is not uniform and the gas barrier property is reduced.

  In addition, there is known a technique for optimizing the heat shrinkage characteristics by optimizing the longitudinal and horizontal stretching conditions and heat treatment conditions of a film and improving the dimensional stability of the ceramic sheet in the production of a ceramic sheet for a release sheet ( For example, see Patent Document 4. However, such a prior art is an example of polyethylene terephthalate that does not use a polyester resin recycled from a PET bottle. However, when a film is formed using a resin material having an intrinsic viscosity of 0.62 dl / g made of the same recycled resin. Since there are variations in the composition inside the film, variations in the laminate surface occur and defects in thickness unevenness occur. Therefore, when an inorganic thin film is deposited on such a polyester film having a large thickness unevenness as a base material, the thickness of the inorganic thin film layer is not uniform, and the gas barrier property is reduced. Further, in order to obtain high lamination strength, the film after biaxial stretching is heat-treated at a high temperature, and a technical idea of cooling after heat treatment is optionally disclosed. However, as a film containing 0.5% by mole or less of 5.0% by mole of isophthalic acid, even if this technology is diverted as it is, the relaxation of the film is uneven in the plane, the thickness unevenness is poor, and the inorganic thin film is similarly deposited. In this case, the thickness of the inorganic thin film layer is not uniform, and the gas barrier property is reduced. In addition, it is disclosed that the flatness of the film is maintained by controlling the refractive index (Nz) in the thickness direction. However, in this document, when polyethylene terephthalate is 100% as a raw material, and Nz is 1.493 or less. The case is assumed. Films containing 0.5% by mole or more and 5.0% by mole or less of isophthalic acid have the advantage of higher lamination strength than 0% by mole polyethylene terephthalate film, but Nz is required to improve both lamination strength and thickness unevenness. There was a problem that this technology could not be diverted as it was because it was too high.

JP 2012-91862 A JP 2001-342267 A JP-A-7-114721 JP 2010-260315 A

The present invention has been made in view of the problems of the related art, that is, an object of the present invention is to provide a laminated film as described below.
1. Laminated plastic resin containing isophthalic acid in a content of 0.5 mol% or more and 5.0 mol% or less, high melt viscosity, solid-state polymerization, and recycling PET bottles that often contain high crystallization nucleating agents Even when used as a raw material resin for a base film in a film, the extrusion temperature is stabilized by optimizing the extrusion temperature, and the resin, additives and particles in the film are homogenized, so that the base film And to improve the lamination strength by reducing the unevenness of the thickness of the laminate.
2. High-magnification longitudinal stretching at a high temperature enables high-magnification transverse stretching even if the melt viscosity of the extruded resin is high, and reduces thickness unevenness of the base film.
3. By performing the lateral stretching at a high temperature, even if the melt viscosity of the resin after extrusion is high, the lateral stretching can be performed at a high magnification and the thickness unevenness of the base film can be reduced.
4. Lowering the heat shrinkage in the vertical and horizontal directions of the base film by performing high-temperature heat treatment.
5. Achieve high lamination strength by adjusting the refractive index in the thickness direction of the base film by high-temperature, high-magnification stretching and high-temperature heat treatment.
6. Slow cooling after heat treatment to reduce the thickness unevenness of a base film containing 0.5% by mole or more and 5.0% by mole or less of isophthalic acid as an acid component. In addition, the lamination strength does not vary within the film.
7. Even in the case of a gas barrier laminate film having an inorganic thin film layer and a sealant layer, polyester recycled from a PET bottle that has a small thickness unevenness, a uniform thickness of the inorganic thin film layer due to a low heat shrinkage, and good gas barrier properties An object is to provide an excellent laminated film using a resin.

The present inventor has conducted intensive studies to achieve the object, and as a result, completed the present invention. That is, the present invention has the following configuration.
1. An inorganic thin film layer and a sealant layer are laminated on at least one surface of the base film in this order, and the base film is made of a polyester resin recycled from a PET bottle in an amount of 50% by weight or more and 95% by weight or more. % Or less, and the content of the inorganic particles in the base film is 0.01% by weight or more and 1% by weight or less, and the polyester film is biaxially stretched, and satisfies the following requirements. Characterized laminated film.
(1) The content of the isophthalic acid component to all dicarboxylic acid components in all the polyester resins constituting the base film is 0.5 mol% or more and 5.0 mol% or less. (2) The limiting viscosity of the resin constituting the base film is 0.58 dl / g or more and 0.70 dl / g or less (3) The laminated film has a water vapor permeability of 5.0 g / m ² · day or less and an oxygen permeability of 40.0 ml / m ² · day · MPa or less (4) 1. The refractive index in the thickness direction of the base film is 1.4930 or more. The thickness Tn of the base film in which the heat shrinkage at 150 ° C. in the vertical and horizontal directions is 0.1% or more and 1.5% or less, and the 1 m length of the base film in the vertical and horizontal directions is measured every 5 mm. (n = 1 to 200) (unit: μm) Measure 200 points, and when the maximum thickness at this time is Tmax, the minimum thickness is Tmin, and the average thickness is Tave, the thickness unevenness obtained by the following formula is 2. The laminated film according to the above item 1, wherein the content is 16% or less in each of a transverse direction and a transverse direction.
Thickness unevenness = {(Tmax-Tmin) / Tave} x 100 (%)
3. 3. The laminated film according to the above 1 or 2, wherein the inorganic thin film layer is composed of two kinds of metals, two kinds of inorganic oxides, or one kind of metal and one kind of inorganic oxide.
4. 3. The laminated film according to the above 1 or 2, wherein the inorganic thin film layer is made of silicon oxide and aluminum oxide.
5. The laminated film according to any one of the first to fourth aspects, wherein the sealant layer is made of a polyolefin-based resin.

  The polyester film using the polyester resin recycled from the PET bottle according to the present invention has a small thickness unevenness even when a gas barrier laminate film having an inorganic thin film layer and a sealant layer is used, and has a low heat shrinkage ratio, thereby reducing the thickness of the inorganic thin film layer. The object of the present invention is to provide an excellent laminated film using a polyester resin recycled from a PET bottle exhibiting good gas barrier properties.

It is a schematic diagram which shows one aspect inside the extruder of the film-forming equipment in this invention.

  The biaxial stretching method is not particularly limited, and a tubular method, a simultaneous biaxial stretching method, or the like can be employed. The sequential biaxial stretching method is preferred.

The lower limit of the intrinsic viscosity of the resin constituting the film obtained by measuring the base film is preferably 0.58 dl / g, more preferably 0.60 dl / g. If the viscosity is less than 0.58 dl / g, many of the recycled resins composed of PET bottles have an intrinsic viscosity exceeding 0.68 dl / g, and if the viscosity is reduced when a film is produced using the resin, the thickness unevenness becomes poor. Is not preferred. Further, the film may be colored, which is not preferable. The upper limit is preferably 0.70 dl / g, more preferably 0.68 dl / g. If it exceeds 0.70 dl / g, it is not preferable because the resin from the extruder becomes difficult to be discharged and productivity may be reduced.
Here, in the present invention, as described later, it is a preferable embodiment to use a recycled polyester resin recycled from a PET bottle containing an isophthalic acid component as an acid component as a raw material of a base film. Therefore, the base film becomes a mixed resin of the recycled polyester resin and the virgin raw material, that is, the non-recycled resin. It means the value obtained by measuring the viscosity.

  The lower limit of the thickness of the base film is preferably 8 μm, more preferably 10 μm, and still more preferably 12 μm. When the thickness is less than 8 μm, the strength as a film may be insufficient, which is not preferable. The upper limit is preferably 200 μm, more preferably 50 μm, and even more preferably 30 μm. If it exceeds 200 μm, it may be too thick and processing may be difficult.

  The lower limit of the refractive index in the thickness direction of the base film is preferably 1.4930, and more preferably 1.4940. If it is less than 1.4930, the orientation may not be sufficient and the laminate strength may not be obtained. The upper limit is preferably 1.4995, more preferably 1.4980. If it exceeds 1.4995, the orientation of the plane is lost, and the mechanical properties may be insufficient.

  The lower limit of the heat shrinkage of the base film in the longitudinal direction (may be described as MD) and the transverse direction (may be described as TD) at 150 ° C. for 30 minutes is preferably 0.1%, more preferably Is 0.3%. If it is less than 0.1%, the effect of improvement is saturated, and it may be mechanically brittle, which is not preferable. The upper limit is preferably 1.5%, more preferably 1.2%. If it exceeds 1.5%, dimensional changes during processing such as printing may cause a pitch shift or the like, which is not preferable. On the other hand, if it exceeds 1.5%, shrinkage in the width direction may occur due to dimensional change during processing such as printing, which is not preferable.

The thickness of the base film was measured at 200 points up to each thickness Tn (n = 1 to 200) (unit: μm) measured in 5 mm increments in the vertical and horizontal directions, and the maximum thickness at this time was Tmax and the minimum thickness was Tmin. When the average thickness is Tave, the thickness unevenness determined by the following equation is preferably 16% or less, more preferably 12% or less, and even more preferably 10% or less in each of the vertical and horizontal directions. If it exceeds 16%, it is not preferred because the film roll may be displaced or the peeled surface may have poor appearance when the laminated portion is peeled off, and the commercial value may be reduced.
Thickness unevenness = {(Tmax-Tmin) / Tave} x 100 (%)

  As a raw material for the base film, it is preferable to use a recycled polyester resin composed of a PET bottle containing an isophthalic acid component as an acid component. The polyester used for PET bottles is controlled for crystallinity in order to improve the appearance of the bottle, and as a result, a polyester containing 10% by mole or less of isophthalic acid component may be used. . In order to utilize a recycled resin, a material containing an isophthalic acid component may be used in some cases.

  The lower limit of the amount of the terephthalic acid component in the total dicarboxylic acid component constituting the polyester resin contained in the base film is preferably 95.0 mol%, more preferably 96.0 mol%, and still more preferably 96.5 mol%. And particularly preferably 97.0 mol%. If it is less than 95.0 mol%, the crystallinity is reduced, and the heat shrinkage may be increased, which is not preferred. The upper limit of the amount of the terephthalic acid component of the polyester resin contained in the film is preferably 99.5 mol%, more preferably 99.0 mol%. Recycled polyester resin made of PET bottles often has a dicarboxylic acid component other than terephthalic acid typified by isophthalic acid. Therefore, if the terephthalic acid component of the polyester resin in the film exceeds 99.5 mol%, it must be recycled. As a result, the production of a polyester film having a high proportion of resin becomes difficult, which is less preferable.

  The lower limit of the amount of the isophthalic acid component in the total dicarboxylic acid component constituting the polyester resin contained in the base film is preferably 0.5 mol%, more preferably 0.7 mol%, and still more preferably 0.9 mol%. And particularly preferably 1.0 mol%. Since some recycled polyester resins made of PET bottles contain a large amount of isophthalic acid component, the fact that the isophthalic acid component constituting the polyester resin in the film is less than 0.5% by mole means that a polyester film having a high ratio of recycled resin is used. Manufacturing is difficult as a result and is less preferred. The upper limit of the amount of the isophthalic acid component in the total dicarboxylic acid component constituting the polyester resin contained in the film is preferably 5.0 mol%, more preferably 4.0 mol%, and still more preferably 3.5 mol%. And particularly preferably 3.0 mol%. If it exceeds 5.0 mol%, the crystallinity is reduced, and the heat shrinkage may increase, which is not preferred. Further, by setting the content of the isophthalic acid component in the above range, it is easy to prepare a film having excellent lamination strength, shrinkage, and thickness unevenness, which is preferable.

  The upper limit of the intrinsic viscosity of the recycled resin made of PET bottles is preferably 0.90 dl / g, more preferably 0.80 dl / g, further preferably 0.77 dl / g, and particularly preferably 0.75 dl / g. . If it exceeds 0.9 dl / g, the resin from the extruder becomes difficult to be discharged, and the productivity may decrease, which is not preferred.

  The lower limit of the content of the polyester resin recycled from the PET bottle to the film is preferably 50% by weight, more preferably 65% by weight, and further preferably 75% by weight. If the content is less than 50% by weight, the content of the recycled resin is poor, and it is not preferable in terms of contribution to environmental protection. The upper limit of the content of the polyester resin recycled from the PET bottle is preferably 95% by weight, more preferably 90% by weight, and further preferably 85% by weight. If the content exceeds 95% by weight, a lubricant or an additive such as inorganic particles may not be sufficiently added for improving the function as a film, which is not preferable. In addition, a polyester resin recycled from a PET bottle can be used as a masterbatch (resin having a high concentration) used when a lubricant or an additive such as inorganic particles is added for improving the function as a film.

  As the kind of lubricant, in addition to inorganic lubricants such as silica, calcium carbonate, and alumina, organic lubricants are preferable, and silica and calcium carbonate are more preferable. With these, transparency and slipperiness can be exhibited.

  The lower limit of the lubricant content in the base film is preferably 0.01% by weight, more preferably 0.015% by weight, and still more preferably 0.02% by weight. If the amount is less than 0.01% by weight, the slipperiness may decrease. The upper limit is preferably 1% by weight, more preferably 0.2% by weight, and even more preferably 0.1% by weight. If it exceeds 1% by weight, transparency may be reduced, which is not preferred.

  The method for producing the substrate film used in the laminated film of the present invention is not particularly limited, but for example, the following production method is recommended. Temperature setting for melting and extruding the resin in the extruder is important. The basic idea is that (1) Since the polyester resin used for PET bottles contains an isophthalic acid component, it is extruded at the lowest possible temperature to suppress deterioration. In order to sufficiently and uniformly melt the conductive portion, it is necessary to have a portion that melts at high temperature or high pressure. The inclusion of the isophthalic acid component lowers the stereoregularity of the polyester, leading to a lowering of the melting point. Therefore, in extrusion at a high temperature, the melt viscosity is significantly reduced or deteriorated due to heat, resulting in a decrease in mechanical strength and an increase in deteriorated foreign matter. Also, simply lowering the extrusion temperature does not allow sufficient melt-kneading, which may cause an increase in thickness unevenness and foreign matters such as fish eyes. From the above, as a recommended manufacturing method, for example, a method using two extruders in tandem, a method of increasing the pressure in the filter section, a method of using a screw having a strong shearing force as a part of the screw configuration, and the like. No. Hereinafter, an example of controlling the temperature using one extruder will be described.

  FIG. 1 shows an embodiment of the inside of an extruder of a film forming facility according to the present invention. In the screw 1 having the flight 2 between the barrels 3, there are a supply unit 4, a compression unit 5, and a measuring unit 6 from the screw root to the tip. The compression section 5 is a region where the space between the screw 1 and the barrel 3 becomes narrower. In the present invention, the set temperature of the supply section 4 and the measuring section 6 is set as low as possible, and the set temperature of the compression section 5 is set high. It is preferable to sufficiently melt and knead the material in the compression section 5 having a high shear, and to take measures to prevent thermal deterioration in the supply section 4 and the measurement section 6.

  The lower limit of the set temperature of the resin melting section in the extruder (excluding the highest set temperature of the compression section of the screw in the extruder) is preferably 270 ° C, and the upper limit is preferably 290 ° C. If the temperature is lower than 270 ° C., it is difficult to extrude. If the temperature is higher than 290 ° C., the resin may be deteriorated.

  The lower limit of the highest set temperature of the compression section of the screw in the extruder is preferably 295 ° C. Polyester resins used for PET bottles often have high melting point crystals (260 ° C. to 290 ° C.) in terms of transparency. In addition, additives and crystallization nucleating agents are added, and the fine melting behavior in the resin material varies. If the temperature is lower than 295 ° C., it becomes difficult to sufficiently melt them, which is not preferred. The upper limit of the maximum set temperature of the compression section of the screw in the extruder is preferably 310 ° C. If the temperature exceeds 310 ° C., the resin may deteriorate, which is not preferable.

  The lower limit of the time for the resin to pass through the region of the highest set temperature in the compression section of the screw in the extruder is preferably 10 seconds, and more preferably 15 seconds. If the time is less than 10 seconds, the polyester resin used for the PET bottle cannot be sufficiently melted, which is not preferable. The upper limit is preferably 60 seconds, more preferably 50 seconds. If the time exceeds 60 seconds, the resin tends to deteriorate, which is not preferable. By setting the setting of the extruder in such a range, it is possible to obtain a film with less foreign matter such as uneven thickness and fish eyes and less coloring while using a large amount of polyester resin recycled from PET bottles.

  The resin melted in this way is extruded into a sheet on a cooling roll and then biaxially stretched. As a stretching method, a simultaneous biaxial stretching method may be used, but a sequential biaxial stretching method is particularly preferable. These make it easy to satisfy the productivity and the quality required for the present invention.

  In the present invention, the stretching method of the film is not particularly limited, but the following points are important. In order to stretch a resin having an intrinsic viscosity of 0.58 dl / g or more and containing an isophthalic acid component, the magnification and temperature in the longitudinal (MD) stretching and transverse (TD) stretching are important. If the MD stretching ratio or temperature is not appropriate, the stretching force is not uniformly applied, the orientation of the molecules becomes insufficient, the thickness unevenness may increase, and the mechanical properties may become insufficient. Further, in the next TD stretching step, the film may be broken or the thickness unevenness may be extremely increased. If the TD stretching ratio and the temperature are not appropriate, the film may not be stretched uniformly, the orientation balance in the vertical and horizontal directions may be poor, and the mechanical properties may be insufficient. In addition, if the process proceeds to the next heat fixing step in a state where the thickness unevenness is large or the orientation of the molecular chains is insufficient, uniform relaxation cannot be achieved, and further increase in the thickness unevenness and insufficient mechanical properties. Problem arises. For this reason, it is basically recommended that MD stretching be performed in a stepwise manner by performing the temperature control described below, and that TD stretching be performed at an appropriate temperature so that the orientation balance is not extremely deteriorated. Although not limited to the following embodiments, an example will be described.

  As the longitudinal (MD) stretching method, a roll stretching method and an IR heating method are preferable.

  The lower limit of the MD stretching temperature is preferably 100 ° C., more preferably 110 ° C., and even more preferably 120 ° C. If the temperature is lower than 100 ° C., even if the intrinsic viscosity of a polyester resin having a viscosity of 0.58 dl / g or more is stretched and molecularly oriented in the longitudinal direction, the film may be broken in the next transverse stretching step, or extreme thickness defects may occur. It is not preferable. The upper limit is preferably 140 ° C., more preferably 135 ° C., and even more preferably 130 ° C. If the temperature exceeds 140 ° C., the orientation of the molecular chains becomes insufficient, and the mechanical properties may become insufficient.

  The lower limit of the MD stretching ratio is preferably 2.5 times, more preferably 3.5 times, and even more preferably 4 times. If it is less than 2.5 times, even if the intrinsic viscosity of the polyester resin having a viscosity of 0.58 dl / g or more is stretched and the molecules are oriented in the machine direction, the film will break in the next transverse stretching process, or extreme thickness defects will occur. And may not be very desirable. The upper limit is preferably 5 times, more preferably 4.8 times, and even more preferably 4.5 times. If it exceeds 5 times, the effect of improving mechanical strength and thickness unevenness may be saturated, which is not so significant.

  The MD stretching method may be the one-stage stretching described above, but it is more preferable to divide the stretching into two or more stages. By dividing into two or more stages, it is possible to stretch a polyester resin having a high intrinsic viscosity and made of a recycled resin containing isophthalic acid, and to improve the thickness unevenness, the lamination strength, the mechanical properties, and the like.

  The lower limit of the MD stretching temperature of the first step is preferably 110 ° C., and more preferably 115 ° C. When the temperature is lower than 110 ° C., heat is insufficient, longitudinal stretching cannot be sufficiently performed, and flatness is poor. The upper limit of the preferred first-stage MD stretching temperature is 125 ° C, more preferably 120 ° C. If the temperature exceeds 125 ° C., the orientation of the molecular chains becomes insufficient, and the mechanical properties may decrease, which is not preferred.

  The lower limit of the preferred first-stage MD stretching ratio is 1.1 times, and more preferably 1.3 times. When the ratio is 1.1 times or more, the first stage of the weak stretching allows the polyester resin having an intrinsic viscosity of 0.58 dl / g or more to be sufficiently longitudinally stretched, thereby increasing the productivity. The upper limit of the preferred first-stage MD stretching ratio is 2 times, and more preferably 1.6 times. If the ratio is more than twice, the orientation of the molecular chains in the longitudinal direction becomes too high, so that it is difficult to perform stretching in the second and subsequent steps and a film having poor thickness unevenness is not preferred.

  The lower limit of the MD stretching temperature of the second (or final) stage is preferably 110 ° C, more preferably 115 ° C. When the temperature is 110 ° C. or more, a polyester resin having an intrinsic viscosity of 0.58 dl / g or more can be sufficiently stretched in the longitudinal direction, and can be stretched in the next step in the transverse direction. It may be. The upper limit is preferably 130 ° C, more preferably 125 ° C. When the temperature exceeds 130 ° C., crystallization is promoted, and transverse stretching becomes difficult, and thickness unevenness may increase, which is not preferred.

  The lower limit of the MD stretching ratio of the second stage (or the final stage) is preferably 2.1 times, and more preferably 2.5 times. If it is less than 2.1 times, even if the intrinsic viscosity is stretched to 0.58 dl / g or more and the polyester resin is stretched and molecularly oriented in the machine direction, the film will break in the next transverse stretching process or extreme thickness failure will occur. And may not be very desirable. The upper limit is preferably 3.5 times, more preferably 3.1 times. If it exceeds 3.5 times, the longitudinal orientation becomes too high, so that stretching in the second and subsequent steps may not be possible or the film may have a large thickness unevenness, which is not preferred.

  The lower limit of the TD stretching temperature is preferably 110 ° C, more preferably 120 ° C, and even more preferably 125 ° C. If the temperature is lower than 110 ° C., the stretching stress in the transverse direction is increased, and the film may be broken or the thickness unevenness may be extremely large. The upper limit is preferably 150 ° C, more preferably 145 ° C, and even more preferably 140 ° C. If the temperature exceeds 150 ° C., the orientation of the molecular chains does not increase, so that the mechanical properties may decrease, which is not preferred.

  The lower limit of the transverse (TD) stretch ratio is preferably 3.5 times, and more preferably 3.9 times. If it is less than 3.5 times, the molecular orientation is weak and the mechanical strength may be insufficient, which is not preferred. In addition, the orientation of the molecular chains in the vertical direction is large, and the balance in the vertical and horizontal directions is deteriorated. The upper limit is preferably 5.5 times, more preferably 4.5 times. If it exceeds 5.5 times, it may be broken, which is not preferable.

  In order to obtain the substrate film used in the laminated film of the present invention, it is desirable to appropriately set the conditions for the heat setting performed in the tenter after the end of the TD stretching and the conditions for lowering the film to room temperature thereafter. . Polyester film containing recycled resin made of PET bottles containing isophthalic acid has lower crystallinity than ordinary polyethylene terephthalate film not containing isophthalic acid, and is extremely easy to melt very finely. Low. Therefore, when the film is exposed to a high temperature under tension after the completion of stretching or when it is cooled under a tension after the completion of high-temperature heat setting, the tension balance in the width direction is disturbed due to the unavoidable temperature difference in the width direction of the film. In addition, the thickness unevenness and the mechanical properties become poor. On the other hand, if the heat setting temperature is lowered to cope with this phenomenon, sufficient lamination strength may not be obtained. In the present invention, it is recommended that after the completion of the stretching, a slightly lower temperature heat setting 1 and a sufficiently high temperature heat setting 2 (a heat setting 3 if necessary) are provided, followed by a slow cooling step to lower the temperature to room temperature. However, the method is not limited to this method.For example, a method of controlling the film tension in accordance with the speed of the hot air in the tenter and the temperature of each zone, and a heat treatment at a relatively low temperature at which the furnace length is sufficient after the completion of the stretching. And a method of relaxing with a heating roll after completion of heat setting.

  As an example, a method by controlling the temperature of the tenter will be described below.

  The lower limit of the temperature of the heat setting 1 is preferably 160 ° C., more preferably 170 ° C. If the temperature is lower than 160 ° C., the heat shrinkage rate will eventually increase, causing a shift or shrinkage during processing, which is not preferred. The upper limit is preferably 215 ° C, more preferably 210 ° C. If the temperature exceeds 215 ° C., a high temperature is suddenly applied to the film, and the thickness unevenness may be increased or the film may be broken.

  The lower limit of the time for heat setting 1 is preferably 0.5 seconds, and more preferably 2 seconds. If the time is less than 0.5 seconds, the film temperature may be insufficiently increased. The upper limit is preferably 10 seconds, more preferably 8 seconds. If the time is longer than 10 seconds, the productivity may decrease, which is not preferable.

  The lower limit of the temperature of the heat setting 2 is preferably 220 ° C., more preferably 227 ° C. If the temperature is lower than 220 ° C., the heat shrinkage rate becomes large, which may cause misalignment or shrinkage during processing, which is not preferable. The upper limit is preferably 240 ° C, more preferably 237 ° C. If the temperature exceeds 240 ° C., the film may be melted, and if not melted, the film may become brittle, which is not preferred.

  The lower limit of the time for heat setting 2 is preferably 0.5 seconds, and more preferably 3 seconds. If the time is less than 0.5 seconds, breakage may easily occur during heat setting, which is not preferred. The upper limit is preferably 10 seconds, more preferably 8 seconds. If the time exceeds 10 seconds, sagging or the like may occur and uneven thickness may occur, which is not preferable.

  If necessary, the lower limit of the temperature when the heat setting 3 is provided is preferably 205 ° C., and more preferably 220 ° C. When the temperature is lower than 205 ° C., the heat shrinkage rate is increased, and the resulting material may be displaced or shrunk during processing, which is not preferable. The upper limit is preferably 240 ° C, more preferably 237 ° C. If the temperature exceeds 240 ° C., the film is melted, and even if it does not melt, the film may become brittle, which is not preferred.

If necessary, the lower limit of the time when the heat setting 3 is provided is preferably 0.5 seconds, and more preferably 3 seconds. If the time is less than 0.5 seconds, breakage may easily occur during heat setting, which is not preferred. The upper limit is preferably 10 seconds, more preferably 8 seconds. If the time exceeds 10 seconds, sagging or the like may occur and uneven thickness may occur, which is not preferable.

  TD relaxation can be performed at any point of heat setting. The lower limit is preferably 0.5%, more preferably 3%. If it is less than 0.5%, the heat shrinkage in the lateral direction becomes particularly large, and there is a possibility that the film will be displaced or shrunk during processing, which is not preferable. The upper limit is preferably 10%, more preferably 8%. If it exceeds 10%, sagging or the like may occur and uneven thickness may occur, which is not so preferable.

  The lower limit of the annealing temperature after the TD heat fixing is preferably 90 ° C, more preferably 100 ° C. If the temperature is lower than 90 ° C., since the film contains isophthalic acid, thickness unevenness may increase or breakage may occur due to shrinkage due to rapid temperature change, which is not preferred. The upper limit of the annealing temperature is preferably 150 ° C, more preferably 140 ° C. If the temperature exceeds 150 ° C., a sufficient cooling effect may not be obtained, which is not preferable.

  The lower limit of the annealing time after heat setting is preferably 2 seconds, and more preferably 4 seconds. If the time is less than 2 seconds, a sufficient slow cooling effect may not be obtained, so that it is not so preferable. The upper limit is preferably 20 seconds, more preferably 15 seconds. If the time exceeds 20 seconds, it tends to be disadvantageous in terms of productivity, which is not so preferable.

  The laminated film of the present invention has an embodiment in which an inorganic thin film layer is laminated on one surface of a polyester film serving as a base material, and a polyolefin-based resin layer is further laminated on the inorganic thin film layer. That is, the laminated film of the present invention is used for a gas barrier laminated film provided with an inorganic thin film layer and a polyolefin resin layer, and has an embodiment in which the inorganic thin film layer and the polyolefin resin layer are laminated in advance.

  In the laminated film of the present invention, for the purpose of imparting gas barrier properties, it is necessary to laminate an inorganic thin film layer on one surface of a polyester film serving as a substrate, on which, via an adhesive layer or The sealant layer is laminated without any intervention.

  The inorganic thin film layer is a thin film made of a metal or an inorganic oxide. The material for forming the inorganic thin film layer is not particularly limited as long as it can be formed into a thin film, but from the viewpoint of processability and gas barrier properties, it is preferable to use a material containing aluminum. Examples of the material containing aluminum include highly pure aluminum (99.9 mol% or more), an aluminum alloy containing another additive element, an inorganic oxide such as aluminum oxide, and the like. Or a combination of a plurality of inorganic oxides. The combination of materials for forming the inorganic thin film layer is not particularly limited. For example, two kinds of metals, two kinds of inorganic oxides, or a combination of one kind of metal and one kind of inorganic oxide are employed. it can. For example, high-purity aluminum and aluminum alloy, two kinds of aluminum alloys (additional elements such as magnesium, silicon, titanium, calcium, and manganese) with different additive elements, aluminum alloy and aluminum oxide, aluminum oxide and titanium oxide, silicon oxide and oxide Aluminum and the like can be mentioned, but a composite oxide of silicon oxide (silica) and aluminum oxide (alumina) is preferable from the viewpoint that both flexibility and denseness of the thin film layer can be achieved.

  The thickness of the inorganic thin film layer is usually from 1 nm to 800 nm, preferably from 5 nm to 500 nm. If the thickness of the metal thin film layer is less than 1 nm, it may be difficult to obtain a satisfactory gas barrier property. On the other hand, if the thickness exceeds 800 nm, the effect of improving the gas barrier property is obtained. This 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, for example, a known deposition method such as 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 appropriately adopted. Hereinafter, a typical method for forming an inorganic thin film layer will be described by taking a silicon oxide / aluminum oxide-based thin film as an example. For example, when a vacuum 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 a deposition material. Particles are usually used as these vapor deposition raw materials. At this time, the size of each particle is desirably such that the pressure during vapor deposition does not change, and the preferred particle diameter is 1 mm to 5 mm. For heating, a method such as resistance heating, high-frequency induction heating, electron beam heating, or laser heating can be employed. It is also possible to introduce oxygen, nitrogen, hydrogen, argon, carbon dioxide gas, water vapor, or the like as a reaction gas, or to employ reactive vapor deposition using means such as ozone addition or ion assist. Further, the film formation conditions can be arbitrarily changed, such as applying a bias to the object to be deposited (a laminated film to be subjected to evaporation), or heating or cooling the object to be deposited. Such deposition material, reaction gas, bias of the object to be deposited, heating / cooling, and the like can be similarly changed when a sputtering method or a CVD method is employed.

  As described above, on the polyester film as the base film, an inorganic thin film layer is laminated, and then, on the inorganic thin film layer, a sealant layer is laminated with or without an adhesive layer. It is composed of polyolefin resin.

  This sealant layer is formed by laminating an inorganic thin film layer on one surface of a base film, and further bonding a film made of a polyolefin resin via an adhesive onto the inorganic thin film layer surface. It may be carried out, or may be directly laminated by extrusion lamination of a polyolefin resin.

  Here, the polyolefin-based resin in the present invention is a resin obtained by polymerizing or copolymerizing an olefin monomer, and the content of the unit constituting the polymer derived from these olefin monomers is the total copolymer mass. Represents a resin occupying 80% by weight or more, more preferably 90% by weight or more, most preferably a resin occupying substantially 100%, preferably ethylene, propylene, butene-1, pentene-1, 4-methyl. Examples thereof include polymers composed of α-olefins such as pentene-1, hexene-1, and octene-1, and random copolymers and block copolymers thereof.

  Among the random copolymers, the propylene random copolymer is a polymer in which propylene and at least one other α-olefin monomer are randomly copolymerized, for example, by a known method, other than propylene. There is a polypropylene in which one or more α-olefin monomers are copolymerized in a range of 2 to 15% by weight.

  In the block copolymer, a propylene-ethylene-block copolymer is a copolymer composed of propylene and a small amount of ethylene and / or another α-olefin, and a copolymer composed of a small amount of propylene and ethylene. The polymer portion is a block copolymerized with a polymer portion. The composition of each copolymer component, the molecular weight of each block, etc. can be controlled at the polymerization stage. Generally, it can be obtained by a polymerization method having two or more stages as disclosed in JP-A-59-11512. For example, the melting point of the propylene block copolymer ranges from 145 to 165 ° C. The melting point can be varied by the amount of the polypropylene component of the copolymer portion comprising abundant amounts of propylene and small amounts of ethylene and / or other α-olefins.

  As the polyolefin-based resin constituting the polyolefin-based resin layer, a simple polymer is preferably polyethylene, more preferably low-density polyethylene, and particularly preferably linear low-density polyethylene. In the random copolymer, a propylene / random copolymer is preferred, and a copolymer of propylene and ethylene or butene-1 is particularly preferred. The proportion of the copolymer component is preferably in the range of 2 to 15% by weight. . Among the block copolymers, a polypropylene block copolymer is preferable, and a copolymer of polypropylene, ethylene, and butene-1 is particularly preferable. The copolymer is preferably used in a proportion of 5 to 20% by weight. The melting point of these polyolefin resins is preferably in the range of 110 to 165 ° C from the viewpoint of heat sealing properties.

In the laminated film of the present invention, an inorganic thin film layer is laminated on one surface of a polyester film serving as a base material, and a sealant layer is laminated thereon with or without an adhesive layer. When laminating a sealant layer through the intermediary, a known coating agent is used for forming the adhesive layer. For example, coating agents such as isocyanate-based, polyurethane-based, polyester-based, polyethyleneimine-based, polybutadiene-based, polyolefin-based, and alkyl titanate-based coating agents can be used. In consideration of effects such as adhesion, heat resistance, and water resistance among these, isocyanate-based, polyurethane-based, and polyester-based coating agents are preferable, and one or a mixture of two or more of isocyanate compounds, polyurethane, and urethane prepolymers And a reaction product, a mixture and a reaction product of one or more of polyester, polyol and polyether with an isocyanate, or a solution or dispersion thereof.

The thickness of the adhesive layer in order to increase sufficiently the adhesion between the sealant layer is preferably 0.1g / m ² ~3g / m ² at least dry thickness, more preferably 0.5g / m ² ~2. A range of 5 g / m ² is preferred. When the dry thickness is 3 g / m ² or more, high adhesion cannot be obtained, which is not preferable.

  The method for applying the adhesive layer is not particularly limited, and ordinary methods such as gravure roll coating, reverse roll coating, wire bar coating, and air knife coating can be used.

The water vapor permeability (g / m ² · day) of the laminated film is preferably 5 or less, more preferably 4 or less. If the oxygen permeability of the laminated film exceeds 5, sufficient gas barrier properties cannot be obtained.

The oxygen permeability (ml / m ² · day · MPa) of the laminated film is preferably 40 or less, more preferably 30 or less. If the oxygen permeability of the laminated film exceeds 40, sufficient gas barrier properties cannot be obtained.

  The laminated film of the present invention as described above has a gas barrier laminated film (laminate) having excellent oxygen barrier properties and water vapor barrier properties by having an inorganic thin film layer in the structure of the laminated film.

  Further, in the laminated film, at least one or more printed layers or other plastic substrates and / or paper substrates are laminated between or outside the inorganic thin film layer or the base film and the heat-sealing resin layer. Is also good.

As the printing ink for forming the printing layer, aqueous and solvent-based resin-containing printing inks can be preferably used. Here, 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. Printing inks include known antistatic agents, light-blocking agents, ultraviolet absorbers, plasticizers, lubricants, fillers, colorants, stabilizers, lubricants, defoamers, crosslinking agents, anti-blocking agents, antioxidants, etc. May be added. The printing method for providing the printing layer is not particularly limited, and a known printing method such as an offset printing method, a gravure printing method, and a screen printing method can be used. Known drying methods such as hot-air drying, hot-roll drying, and infrared drying can be used for drying the solvent after printing.

On the other hand, as another plastic substrate or paper substrate, paper, polyester resin, polyamide resin, biodegradable resin, and the like are preferably used from the viewpoint of obtaining sufficient rigidity and strength of the laminate. In order to obtain a film having excellent mechanical strength, a stretched film such as a biaxially stretched polyester film or a biaxially stretched nylon film is preferable.

  Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The evaluation method used in the present invention is as follows.

(1) Content of terephthalic acid and isophthalic acid components contained in the raw material polyester and the polyester constituting the film Chloroform D (manufactured by Yurisop) and trifluoroacetic acid D1 (manufactured by Yurisop) are 10: 1 (volume ratio). A sample solution was prepared by dissolving the raw material polyester resin or polyester film in the mixed solvent. Then, the prepared sample solution was subjected to NMR measurement of protons of the sample solution using an NMR apparatus (nuclear magnetic resonance spectrometer manufactured by Varian: GEMINI-200) at a temperature of 23 ° C. and 64 times of integration. In the NMR measurement, the peak intensity of a predetermined proton was calculated, and the content (mol%) of the terephthalic acid component and the isophthalic acid component in 100 mol% of the acid component was calculated.

(2) Intrinsic viscosity (IV) of raw resin and resin constituting film
The sample was vacuum-dried at 130 ° C. all day and night, and then crushed or cut, 80 mg of the sample was precisely weighed, and dissolved by heating at 80 ° C. for 30 minutes in a mixed solution of phenol / tetrachloroethane = 60/40 (volume ratio). After heating and dissolving at 80 ° C., the mixture was cooled to room temperature, and the mixed solvent prepared in the above ratio was added to a volume of 20 ml in a volumetric flask, followed by measurement at 30 ° C. (unit: dl / g). An Ostwald viscometer was used to measure the intrinsic viscosity.

(3) Base film thickness
Using a PEACOCK dial gauge (manufactured by Ozaki Seisakusho), measure the thickness Tn (n = 1 to 200) (μm) of the film 1m in the vertical and horizontal directions every 5mm at 200 points, and use the average value as the base material The thickness of the film.

(4) Heat shrinkage in the vertical and horizontal directions of the base film The base film was sampled at a width of 10 mm, and marked at 200 mm intervals at room temperature (27 ° C.). After the measurement (L 0), the film was sandwiched between papers, placed in a hot-air oven controlled at a temperature of 150 ° C., treated for 30 minutes, taken out, and then measured for the interval between marked lines (L). The heat shrinkage was determined from the following equation. Samples are collected in both the vertical and horizontal directions.

Heat shrinkage (%) = {(L0−L) / L0} × 100

(5) Refractive index in the thickness direction of the base film
The refractive index (Nz) in the thickness direction was determined using Abbe refractometer NAR-1T (manufactured by Atago Co., Ltd.) in accordance with JIS K7142. The light source was a sodium D line, a test piece with a refractive index of 1.74, and methylene iodide as an intermediate liquid.

(6) Uneven thickness of base film
Using a PEACOCK dial gauge (manufactured by Ozaki Seisakusho), measure the thickness Tn (n = 1 to 200) (μm) of the film 1m length in the vertical and horizontal directions every 5mm at 200 points, and determine the maximum thickness at this time. Tmax, minimum thickness Tmin, and average thickness Tave were determined from the following equation (1).
Thickness unevenness = {(Tmax−Tmin) / Tave} × 100 (%) (1)

(7) Evaluation Method of Water Vapor Permeability of Laminated Film For a laminated film having an inorganic thin film layer and a sealant layer, a water vapor permeability measuring device (“PERMATRAN-W 3 / 33MG manufactured by MOCON”) was used in accordance with JIS-K7129-B method. )), Under normal conditions (normal conditions without external stress or force) in an atmosphere in which the temperature and humidity on the high humidity side around the sample at the time of measurement are 40 ° C. and 90% RH, respectively. Was measured for water vapor transmission rate. The measurement of the water vapor permeability was performed in the direction in which water vapor permeated from the biaxially stretched polyester film side to the inorganic thin film layer side.

(8) Evaluation method of oxygen permeability of laminated film For a laminated film having an inorganic thin film layer and a sealant layer, an oxygen permeability measuring device (MOCON Inc.) according to the electrolytic sensor method of JIS-K7126-1 (Appendix A). "OX-TRAN 2/20" manufactured by Okayama Co., Ltd.), the oxygen permeability under normal conditions was measured in an atmosphere in which the temperature and humidity on the high humidity side around the sample at the time of measurement were 23 ° C. and 65% RH, respectively. . The oxygen permeability was measured in the direction in which oxygen permeated from the biaxially stretched polyester film side to the metal thin film layer side.

(9) Evaluation Method of Thickness of Inorganic Thin Film Layer The thickness of the inorganic thin film layer was determined by a fluorescent X-ray analysis method using a calibration curve prepared in advance using a film having a known thickness. Several kinds of metal thin films having different film thicknesses and compositions were prepared, and measured with a fluorescent X-ray apparatus to obtain a calibration curve for film thickness measurement. The fluorescent X-ray analysis conditions were such that the tube voltage was 50 kV and the tube current was 40 mA as conditions for the excitation X-ray tube.

(Example 1)
(Adjustment of polyester resin recycled from PET bottles)
After washing off the remaining foreign substances such as beverages from the PET bottle for beverages, the flakes obtained by grinding are melted by an extruder, and the filter is sequentially changed to a finer one with a smaller opening size to filter out the finer foreign substances twice. Separately, the polyester was filtered through a filter having the smallest opening size of 50 μm for the third time to obtain a recycled polyester raw material. The composition of the obtained resin was terephthalic acid / isophthalic acid // ethylene glycol = 97.0 / 3.0 // 100 (mol%), and the intrinsic viscosity of the resin was 0.70 dl / g. This is designated as polyester A.

(Preparation of film)
Polyester terephthalate resin of intrinsic viscosity 0.62 dl / g composed of terephthalic acid // ethylene glycol = 100 // 100 (mol%) as polyester B, and polyester B as amorphous silica having an average particle diameter of 1.5 μm Was prepared as a master batch containing 0.3%. Each raw material was dried at 125 ° C. for 8 hours under a reduced pressure of 33 Pa. What mixed them so that A / B / C = 70/20/10 (weight ratio) was put into a single screw extruder. The temperature from the extruder to the melt line, the filter and the T-die was set so that the temperature of the resin was 280 ° C. However, the temperature of the resin was set to 305 ° C. for 30 seconds from the start point of the compression section of the screw of the extruder, and then to 280 ° C. again.

The melt extruded from the T-die was brought into close contact with a cooling roll to form an unstretched sheet, which was subsequently stretched 1.41 times in the longitudinal direction by a roll having a peripheral speed difference heated to 118 ° C (MD1). Further, it was stretched 2.92 times (MD2) in the longitudinal direction by a roll heated at 128 ° C. and having a difference in peripheral speed. The longitudinally stretched sheet was guided to a tenter, preheated at 121 ° C., and then transversely stretched 4.3 times at 131 ° C. Subsequently, as heat fixation, it was performed at 180 ° C., without relaxation (0%) for 2.5 seconds (TS1), then at 231 ° C., 5% relaxation, and after 3.0 seconds (TS2), then at 222 ° C. without relaxation. Performed for 2.5 seconds (TS3). Subsequently, the resultant was cooled at 120 ° C. for 6.0 seconds in the same tenter, and finally wound up with a winder to obtain a biaxially oriented polyester film having a thickness of 18 μm.

(Formation of inorganic thin film layer)
Next, on one surface of the obtained biaxially stretched polyester film, a composite inorganic oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic thin film layer by an electron beam evaporation method. As an evaporation source, particulate SiO ₂ (purity 99.9%) of about 3 mm to 5 mm and Al ₂ O ₃ (purity 99.9%) were used.
%). The composition herein composite oxide _{layer, SiO 2 / A1 2 O 3} ( mass ratio) = 60 /
It was 40. In addition, the film thickness of the inorganic thin film layer (SiO ₂ / Al ₂ O ₃ composite oxide layer) in the film (inorganic thin film layer / biaxially stretched polyester film) thus obtained was 13 nm.

(Formation of sealant layer)
Next, a laminated film having the obtained inorganic thin film layer and a 40 μm-thick polyethylene film (“L4102” manufactured by Toyobo Co., Ltd.) were coated with a urethane-based adhesive (TM569, CAT10L, manufactured by Toyoh Morton, 33.6% ethyl acetate). : 4.0: 62.4 (weight ratio)), and laminated on the surface of the inorganic thin film layer of the base film by dry lamination, and aged at 40 ° C for 4 days to obtain a laminate. The lamination conditions were such that the line speed was 20 m / min, the dryer temperature was 80 ° C., and the coating amount after drying was 3 g / m ² .

  As described above, the laminated film of the present invention having the inorganic thin film layer and the sealant layer on the biaxially stretched polyester film in this order was obtained. The obtained laminated film was evaluated for oxygen permeability and water vapor permeability as described above.

(Example 2)
An 18 μm-thick biaxially oriented polyester film was applied to a 18 μm-thick polyester film in the same manner as in Example 1 except that the polyester raw materials were mixed so that A / B / C = 80/10/10 (weight ratio). A laminated film having a layer and a sealant layer was obtained.

(Example 3)
Except for 45 seconds from the starting point of the compression part of the screw of the extruder, the temperature of the resin was set to 305 ° C., and a film having a thickness of 12 μm was formed in the same manner as in Example 2 except that the film was 12 μm thick. A laminated film having an inorganic thin film layer and a sealant layer on a stretched polyester film was obtained.

(Examples 4 and 5)
(Adjustment of polyester resin recycled from PET bottles)
After the remaining foreign substances such as beverages were washed off from the beverage PET bottle different from that in Example 1, the flakes obtained by the pulverization were melted by an extruder, and the filter was sequentially changed to a fine-meshed one twice to change the size twice. Further fine foreign substances were separated by filtration, and filtered for the third time with a filter having the smallest opening size of 50 μm to obtain a recycled polyester material. The composition of the obtained resin was terephthalic acid / isophthalic acid // ethylene glycol = 95.0 / 5.0 // 100 (mol%), and the intrinsic viscosity of the resin was 0.70 dl / g. This is polyester D.

(Creation of film)
Except that D / B / C = 60/30/10 (Example 4) and 80/10/10 (Example 5) for the polyester raw material, the final thickness was obtained in the same manner as in Example 1. A laminated film having an inorganic thin film layer and a sealant layer on an 18 μm biaxially stretched polyester film was obtained.

(Example 6)
A laminated film having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film having a thickness of 18 μm was obtained in the same manner as in Example 1 except that an aluminum alloy was formed by an electron beam evaporation method as the inorganic thin film layer. The formation of the inorganic thin film layer is as follows.

(Formation of inorganic thin film layer)
On one surface of the biaxially stretched polyester film obtained in the production of the film of Example 1, an aluminum alloy was formed as an inorganic thin film layer by an electron beam evaporation method. As an evaporation source, an aluminum alloy containing 2 mol% of magnesium was used. The thickness of the inorganic thin film layer (aluminum thin film layer) in the obtained film (inorganic thin film layer / biaxially stretched polyester film) was 13 nm.
As described above, a laminated film of the present invention having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film was obtained. The obtained laminated film was evaluated for oxygen permeability and water vapor permeability as described above.

(Example 7)
An 18 μm-thick biaxially stretched polyester film was formed by the same method as in Example 1 except that an aluminum alloy and silicon dioxide as an inorganic oxide were formed by an electron beam evaporation method as the inorganic thin film layer. Was obtained. The formation of the inorganic thin film layer is as follows.

(Formation of inorganic thin film layer)
On one surface of the biaxially stretched polyester film obtained in the production of the film of Example 1, a composite of an aluminum alloy and silicon dioxide was formed as an inorganic thin film layer by an electron beam evaporation method. As an evaporation source, an aluminum alloy containing 2 mol% of magnesium and particulate SiO2 (purity 99.9%) of about 3 mm to 5 mm were used. Here, the composition of the composite layer was aluminum alloy / silicon dioxide (mass ratio) = 40/60. The film thickness of the inorganic thin film layer (aluminum alloy / silicon dioxide composite layer) in the film (inorganic thin film layer / biaxially stretched polyester film) thus obtained was 13 nm.
As described above, a laminated film of the present invention having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film was obtained. The obtained laminated film was evaluated for oxygen permeability and water vapor permeability as described above.

(Comparative Example 1)
The film after the completion of the transverse stretching was heat-fixed, followed by 231 ° C. and 5% relaxation for 3.0 seconds (TS2), followed by 222 ° C. and 2.5 seconds without relaxation (TS3), followed by TS1 and cooling. A laminated film having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film having a thickness of 18 μm was obtained in the same manner as in Example 2 except that no step was provided.

(Comparative Example 2)
From the extruder, in the same manner as in Example 2, except that the temperature of the resin was set to 280 ° C. in all regions of the melt line, the filter and the T-die, a biaxially oriented polyester having a thickness of 18 μm was used. A laminated film having an inorganic thin film layer and a sealant layer on the film was obtained.

(Comparative Example 3)
By the usual polymerization method, the intrinsic viscosity of the resin was 0.70 dl / g with terephthalic acid / isophthalic acid // ethylene glycol = 90.0 / 10.0 // 100 (mol%). This is designated as polyester E. A laminate having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film having a thickness of 18 μm in the same manner as in Example 2 except that E / B / C = 55/35/10 (weight ratio) was used as a polyester raw material. A film was obtained.

(Comparative Example 4)
The temperature from the extruder to the melt line, the filter and the T-die was set so that the temperature of the resin was 280 ° C. However, the temperature of the resin was set to 305 ° C. for 90 seconds from the start point of the compression section of the screw of the extruder, and thereafter to 280 ° C. again. The melt extruded from the T-die was brought into close contact with a cooling roll to form an unstretched sheet, which was then stretched 1.2 times in the machine direction with a roll having a peripheral speed difference heated to 110 ° C (MD1). Further, the film was stretched 2.8 times (MD2) in the longitudinal direction with a roll having a difference in peripheral speed heated to 120 ° C. The longitudinally stretched sheet was guided to a tenter, preheated at 100 ° C., and then transversely stretched 3.9 times at 105 ° C. Example 2 was followed by heat set at 228 ° C. without relaxation for 3.0 seconds (TS2) and at 228 ° C. at 5.0% relax for 2.5 seconds without TS1 and no cooling step. In the same manner as in 1, a laminated film having an inorganic thin film layer and a sealant layer on a biaxially stretched polyester film having a thickness of 18 μm was obtained.

(Comparative Example 5)
By a usual polymerization method, the intrinsic viscosity of the resin was 0.65 dl / g with terephthalic acid / isophthalic acid // ethylene glycol = 97.0 / 3.0 // 100 (mol%). This is designated as polyester F. As a polyester raw material, F / B / C = 80/10/10 (weight ratio), and the temperature was set from the extruder so that the temperature of the resin was 310 ° C. in all regions of the melt line, the filter, and the T-die. did. The melt extruded from the T-die was brought into close contact with a cooling roll to form an unstretched sheet, which was subsequently stretched 1.6 times in the machine direction with a roll having a peripheral speed difference heated to 126 ° C (MD1). Further, the film is stretched 1.3 times in the longitudinal direction by a roll having a difference in peripheral speed heated to 126 ° C. (MD2), and further stretched 2.3 times in the longitudinal direction by a roll having a difference in peripheral speed heated to 118 ° C. MD3). The longitudinally stretched sheet was guided to a tenter, preheated at 110 ° C., and then transversely stretched 4.6 times at 120 ° C. Thereafter, as heat setting, a biaxial treatment with a thickness of 18 μm was performed in the same manner as in Example 2 except that the treatment was performed at 205 ° C. without relaxation for 5.0 seconds (TS2), and TS1, TS3, and a cooling step were not provided. A laminated film having an inorganic thin film layer and a sealant layer on a stretched polyester film was obtained.

(Comparative Example 6)
The temperature from the extruder to the melt line, the filter and the T-die was set so that the temperature of the resin was 280 ° C. However, the temperature of the resin was set to be 300 ° C. for 70 seconds from the start point of the compression section of the screw of the extruder, and then to 280 ° C. again. The melt extruded from the T-die was brought into close contact with a cooling roll to form an unstretched sheet, which was subsequently stretched 3.9 times in the machine direction by a roll having a peripheral speed difference heated to 107 ° C. (MD1). . The longitudinally stretched sheet was guided to a tenter and preheated at 105 ° C. and 115 ° C. for 2 seconds each, followed by four stretching zones of 120 ° C., 130 ° C., 145 ° C. and 155 ° C., and finally 4.1 in 2 seconds each. The film was stretched twice. Subsequently, heat fixing was performed at 220 ° C. without relaxation (0%) for 2.0 seconds (TS1), followed by 235 ° C. without relaxation for 2.0 seconds (TS2), and subsequently at 195 ° C. and relaxation 2.0. %, 2.5 seconds (TS3). A cooling film is not provided, and a winding film is finally wound up by a winder. Otherwise, in the same manner as in Example 2, a laminated film having an inorganic thin film layer and a sealant layer is formed on a biaxially stretched polyester film having a thickness of 18 μm. Obtained.

(Comparative Example 7)
The polyester raw material was set to B / C = 90/10 (weight ratio), and the temperature was set so that the temperature of the resin from the extruder to the melt line, the filter and the T-die was 280 ° C. However, the temperature of the resin was set to 300 ° C. for 30 seconds from the start point of the compression section of the screw of the extruder, and then to 280 ° C. again. Finally, a laminated film having an inorganic thin film layer and a sealant layer on a biaxially stretched PET film was obtained in the same manner as in Comparative Example 6, except that the thickness was 31 μm.

  The biaxially stretched PET films obtained in Examples 1 to 7 had good thickness unevenness, and the laminated film provided with the inorganic thin film layer and the sealant layer had good water vapor permeability and oxygen permeability, and excellent gas barrier properties. Showed sex.

  On the other hand, in Comparative Example 1, since there was no TS1 and no cooling step, the thickness unevenness was large due to shrinkage due to a rapid temperature change, the thickness of the inorganic thin film layer was not uniform, and the gas barrier property was poor. In Comparative Example 2, since the temperature of the compression portion of the screw was low, sufficient melting could not be performed, thickness unevenness was large, the thickness of the inorganic thin film layer was not uniform, and gas barrier properties were poor. In Comparative Example 3, since the content of the isophthalic acid component was high and the crystallinity was low, the resin was soft, sufficient force was not applied by stretching, the thickness unevenness was large, the thickness of the inorganic thin film layer was not uniform, and the gas barrier was low. Sex was bad. In Comparative Example 4, since the TD stretching temperature was low and there was no cooling step after heat setting, the thickness unevenness was large due to rapid cooling, the thickness of the inorganic thin film layer was not uniform, and the gas barrier property was poor. In Comparative Example 5, MD stretching was performed in three steps, but the extrusion temperature was as high as 310 ° C., the intrinsic viscosity of the film was low, the relaxation by heat fixing was insufficient, the heat shrinkage was high, and the inorganic thin film was thin. The thickness of the layer was not uniform, and the gas barrier property was poor. In Comparative Example 6, since there was no cooling step after heat setting, the thickness unevenness was poor due to rapid cooling, the thickness of the inorganic thin film layer was not uniform, and the gas barrier property was poor. Comparative Example 7 did not use a recycled raw material made of a PET bottle, and thus was gradually cooled by lowering the TS3 temperature, and the thickness unevenness was small, but the refractive index in the thickness direction was low due to insufficient temperature of TS3.

  According to the present invention, it is possible to provide a laminated film using a polyester film containing a polyester resin recycled from a high-quality PET bottle. It is possible to provide a laminated film having excellent gas barrier properties having an inorganic thin film layer and a sealant layer using a polyester film having small lamination strength and thickness unevenness.

DESCRIPTION OF SYMBOLS 1 ... Screw 2 ... Flight 3 ... Barrel 4 ... Supply part 5 ... Compression part 6 ... Measuring part

Claims (5)

An inorganic thin film layer and a sealant layer are laminated on at least one surface of the base film in this order, and the base film is made of a polyester resin recycled from a PET bottle in an amount of 50% by weight or more and 95% by weight or more. % Or less and a biaxially stretched polyester film, wherein the content of the inorganic particles in the base film is 0.01% by weight or more and 1% by weight or less, and satisfies the following requirements. Characterized laminated film.
(1) The content of the isophthalic acid component to all dicarboxylic acid components in all the polyester resins constituting the base film is 0.5 mol% or more and 5.0 mol% or less. (2) The intrinsic viscosity of the resin constituting the base film is 0.58 dl / g or more and 0.70 dl / g or less (3) The water vapor permeability of the laminated film is 5.0 g / m ² · day or less, and the oxygen permeability is 40.0 ml / m ² · day · MPa or less (4) The refractive index in the thickness direction of the base film is 1.4930 or more The thickness Tn of the base film in which the heat shrinkage at 150 ° C. in the vertical and horizontal directions is 0.1% or more and 1.5% or less, and the 1 m length of the film in the vertical and horizontal directions of the base film is measured every 5 mm. (n = 1 to 200) (unit: μm) Measure the 200 points, and when the maximum thickness at this time is Tmax, the minimum thickness is Tmin, and the average thickness is Tave, the thickness unevenness calculated by the following formula is 2. The laminated film according to claim 1, wherein the ratio is 16% or less in each of the transverse direction and the transverse direction.
Thickness unevenness = {(Tmax-Tmin) / Tave} x 100 (%)   The laminated film according to claim 1, wherein the inorganic thin film layer is composed of two kinds of metals, two kinds of inorganic oxides, or one kind of metal and one kind of inorganic oxide.   3. The laminated film according to claim 1, wherein the inorganic thin film layer is made of silicon oxide and aluminum oxide.   The laminated film according to any one of claims 1 to 4, wherein the sealant layer is made of a polyolefin-based resin.