JP2017065264A - Vapor-deposited polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor-deposited polyester film excellent in vapor-deposited processability and excellent in gas barrier property to oxygen, moisture or the like.SOLUTION: There is provided a vapor-deposited polyester film having a vapor-deposited layer on at least one surface of a biaxially oriented polyester film with thickness of 5 to 20 μm and having oxygen permeation amount of 20 ml/mday MPa or less and moisture permeation amount of 2.0 g/m/day or less, where the biaxially oriented polyester film has all following requirements (1) to (4) in specific ranges. (1) a difference (Nx-Ny) between a refractive index Nx in a longitudinal direction and a refractive index Ny in a width direction in overall film width. (2) thermal shrinkage in the longitudinal direction and the width direction when heat treated at 150°C for 30 minutes in overall film width. (3) variation of orientation angle to the film width direction. (4) variation of a difference (oblique shrinkage difference) between thermal shrinkage in +45° direction and thermal shrinkage in -45° direction, when clockwise direction is set as a normal direction with respect to the longitudinal direction when heat treated at 150°C for 30 minutes, with respect to the film width direction.SELECTED DRAWING: None

Description

  The present invention relates to a deposited polyester film excellent in oxygen and water vapor gas barrier properties.

  Conventionally, polyester films are widely used in a wide range of fields such as packaging materials and industrial materials because of their excellent mechanical strength, thermal properties, optical properties, and the like. However, since the polyester film has poor gas barrier properties such as oxygen and water vapor, there is a problem that the contents are deteriorated or deteriorated in packaging applications such as foods, retort products, and pharmaceuticals.

  Therefore, the gas barrier property in oxygen, water vapor | steam, etc. is provided to the polyester film used for a packaging use. Conventionally, as a method for imparting a gas barrier property to a polyester film, a method of laminating a film having a good gas barrier property such as polyvinylidene chloride or polyethylene vinyl alcohol copolymer, a metal oxide such as a metal such as aluminum or aluminum oxide on a polyester film. A method of depositing an object to form a thin film is used. In particular, the polyester film obtained by vapor deposition of the latter metal or metal oxide (hereinafter referred to as vapor deposition polyester film) is excellent in heat resistance and transparency, and is used in many applications.

  Moreover, it is known that the performance of the gas barrier property of the obtained vapor-deposited polyester film is greatly dependent on the surface condition and physical properties of the film as the base material. The surface roughness and the number of protrusions of the polyester film as the base material are known. (For example, refer to Patent Document 1), those for which the thermal shrinkage rate in the longitudinal direction and the width direction of the polyester film (for example, refer to Patent Document 2), and the polyester film for which the amount of oligomer generated in the film is defined The thing (for example, refer patent document 3) etc. by which the outstanding gas barrier film is obtained by using as a base material is proposed.

  In recent years, in order to improve productivity, the process of processing a vapor-deposited polyester film has been promoted to increase the speed and the width and length of a film roll serving as a base material. In particular, when the roll is widened, the influence of heat and tension during processing becomes large, so it is difficult to obtain a vapor-deposited thin film that is stable in the width direction. It is difficult to obtain a vapor-deposited polyester film roll having excellent gas barrier properties. For this reason, there is a demand for uniform physical properties in the roll width direction of the polyester film serving as the base material. In particular, there is a demand for reduction in variations in molecular orientation and thermal shrinkage in the roll width direction and distortion. Therefore, in the above-mentioned Patent Documents 1 to 3, although there are descriptions such as the molecular orientation and thermal shrinkage of the polyester film as the base material, there is no description regarding the variation or distortion of each physical property in the roll width direction. When the width is increased, it is difficult to obtain a vapor-deposited polyester film having excellent gas barrier properties.

  Moreover, the biaxially stretched polyester film is used for this vapor deposition polyester film from the point of mechanical strength or heat resistance. As a typical method for forming a biaxially stretched polyester film, a tubular method, a sequential biaxial stretching method, and a simultaneous biaxial stretching method are generally used. The stretching method is mainly adopted. In this sequential biaxial stretching method, generally, an unstretched polyester sheet is first stretched in the longitudinal direction between rolls having a speed difference obtained by heating the glass sheet to a glass transition point or higher. Then, the film is stretched in the width direction by gripping the end of the film on the clip in the tenter, and then wound in a roll shape through a heat setting process, a heat relaxation process in the width direction, and a cooling process, and biaxial stretching. A polyester film can be obtained. However, in this sequential biaxial stretching method, in the stretching process in the width direction, which is the process in the tenter, heat setting, thermal relaxation, and cooling process, the end portion gripped by the clip and the central portion where the restraining force is relatively small. Because of differences in the longitudinal stretching stress caused by stretching in the width direction, the shrinkage stress in the longitudinal direction generated in the heat setting process, and the tension generated in the tenter, non-uniform physical properties occur in the width direction of the film. The Boeing phenomenon is known. Boeing phenomenon here means that, when viewed geometrically, the straight line drawn in the width direction of the film at the tenter entrance changes to a bow-like curve with the center of the film delayed at the tenter exit. In the biaxially stretched polyester film, the main axis of molecular chain orientation is inclined from the central part toward the end part. Therefore, distortion and variations are generated in the width direction even in heat shrinkage characteristics.

  Up to now, as methods for reducing bowing, for example, a method of heat treatment after transverse stretching, cooling to below the glass transition temperature, a method of lowering the shrinkage stress by lowering the heat setting temperature, a method of increasing the stretching ratio in the width direction, etc. Have been proposed (Patent Documents 4 to 6, Non-Patent Document 1).

JP-A-10-119172 JP 11-010725 A JP 2006-299078 A JP 2004-018588 A JP 2005-014545 A Japanese Patent No. 2936688

Norimura Chisato, Yamada Toshiro, Matsuo Tatsuki, “Analysis of Boeing Phenomenon”, Molding, 1992, Vol. 5, No. 5, pp. 312-317

  However, in the method of providing a cooling zone below the glass transition temperature, the production facility becomes large-scale and complicated, and in the method of lowering the heat setting temperature, the heat shrinkage rate in the longitudinal direction and the width direction becomes large, and vapor deposition is performed. Deformation and wrinkles occur during processing, resulting in partial unevenness and loss of the deposited thin film, resulting in deterioration of gas barrier properties, and the method of increasing the stretching ratio in the width direction breaks the orientation balance in the vertical and horizontal directions. For example, deformation and wrinkles are generated during processing, and gas barrier properties are deteriorated. Therefore, in the above method, it is difficult to improve the molecular orientation balance and the thermal contraction rate suitable for the vapor deposition process, and to improve the inclination of the molecular orientation main axis in the width direction and the distortion and variation of the thermal contraction rate.

  The purpose of the present invention is to improve the above-mentioned problems of the prior art and to use a widened film roll with improved productivity, and is excellent in vapor deposition workability and gas barrier properties such as oxygen and water vapor. Another object is to provide a vapor-deposited polyester film.

  As a result of intensive studies, the present inventors controlled not only the orientation balance and heat shrinkage rate of the polyester film as a base material, but also the inclination of the molecular orientation main axis with respect to the film width direction and the distortion of the heat shrinkage rate. It has been found that the above problems can be achieved.

That is, the vapor deposition polyester film of this invention consists of the following structures.
1. A vapor-deposited polyester film having a vapor-deposition layer on at least one side of a biaxially stretched polyester film having a thickness of 5 to 20 μm, having an oxygen transmission rate of 20 ml / m ² · day · MPa or less and a water vapor transmission rate of 2.0 g / The polyester film characterized by being below m < ² > / day and this biaxially stretched polyester film satisfy | fills all the following requirements (1)-(4).
(1) In the full width of the film, the difference (Nx−Ny) between the refractive index Nx in the longitudinal direction and the refractive index Ny in the width direction is within a range of −0.030 or more and 0.015 or less. The heat shrinkage rate when heat-treated at 150 ° C. for 30 minutes is in the range of 0.8% to 2.0% in the longitudinal direction and −0.5% to 1.0% in the width direction (3 ) The amount of change in the orientation angle with respect to the film width direction is 0 ° or more and 20 ° or less per meter. (4) When heat treated at 150 ° C. for 30 minutes with respect to the film width direction, The amount of change in the film width direction of the difference between the heat shrinkage rate in the + 45 ° direction and the heat shrinkage rate in the −45 ° direction (diagonal heat shrinkage rate difference) with the clockwise direction as the positive direction is 0% or more and 0.25% per meter. Here, in the requirements (1) to (4) Sampling position of the fee, and the position of the intervals of 500mm toward both ends from the center position and a central position with respect to the entire width, when it is not possible to secure the 500mm spacing in the vicinity of both ends, and harvestable end position.
In the requirements (1) and (2), the maximum value and the minimum value of each measurement position data are within the range, and the requirements (3) and (4) are each change amount between two adjacent sampling positions. It is a requirement that the maximum value of is within the range.
2. The vapor-deposited polyester film as described in the above item 1, wherein the vapor-deposited layer is made of a metal or a metal oxide.
3. The vapor-deposited polyester film according to the first or second aspect, wherein the vapor-deposited layer is made of a metal oxide, and the metal oxide is made of aluminum oxide, silicon oxide, or a mixture thereof.
4). 4. The vapor-deposited polyester film according to any one of the first to third aspects, wherein the total film width is 1500 mm or more.
5. The vapor-deposited polyester film according to any one of the first to fourth aspects, wherein particles are contained in the biaxially stretched polyester film.
6). It is a manufacturing method of the vapor deposition polyester film in any one of the said 1st-5th, Comprising: At least single side | surface of the said biaxially-stretched polyester film is subjected to a corona discharge treatment, and the film surface subjected to the corona discharge treatment is subjected to vacuum vapor deposition. A method for producing a vapor-deposited polyester film, comprising depositing a vapor-deposited layer by any one of a sputtering method, a sputtering method, and an ion beam method.

  According to the present invention, a vapor-deposited polyester film excellent in gas barrier properties such as oxygen and water vapor can be obtained even in the use of a wide film roll with improved productivity.

Hereinafter, the present invention will be described in detail.
The base film of the present invention is a biaxially stretched polyester film made of a polyester resin. The polyester resin used in the present invention is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Examples thereof include polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, and polyethylene terephthalate is preferable from the viewpoints of mechanical properties, heat resistance, cost, and the like.

  In addition, other components may be copolymerized with these polyesters as long as the object of the present invention is not impaired. Specifically, examples of the copolymer component include isophthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, adipic acid, sebacic acid, and ester-forming derivatives thereof as dicarboxylic acid components. Examples of the diol component include diethylene glycol, hexamethylene glycol, neopentyl glycol, and cyclohexane dimethanol. Moreover, polyoxyalkylene glycols, such as polyethylene glycol and polypropylene glycol, are also mentioned. The amount of copolymerization is preferably within 10 mol%, more preferably within 5 mol%, per repeating unit.

  As a method for producing the polyester of the present invention, first, esterification or transesterification was carried out according to a conventional method using the above-mentioned dicarboxylic acid or its ester-forming derivative and diol or its ester-forming derivative as main starting materials. Thereafter, a method of producing the product by performing a polycondensation reaction at a higher temperature and reduced pressure may be used.

  The intrinsic viscosity of the polyester of the present invention is preferably in the range of 0.50 to 0.9 dl / g, more preferably in the range of 0.55 to 0.8 dl / g, from the viewpoint of film forming property and recollectability. is there.

  In addition, it is preferable to mix | blend particle | grains with the polyester film used as the base material of this invention from the point of the slipperiness at the time of film forming or a vapor deposition process. Although it does not specifically limit as a particle to mix, For example, inorganic particles, such as silica, calcium carbonate, barium sulfate, calcium sulfate, titanium oxide, kaolin, and talc, are mentioned, cross-linked polystyrene resin, cross-linked acrylic resin, etc. Organic particles may be used.

  In the present invention, the particle size of the particles contained in the polyester film is 0.5 &# 12316 in terms of average particle size (measured by laser diffraction scattering method) from the viewpoints of particle aggregation and transparency, and deterioration of gas barrier properties due to coarse protrusions. A range of 10 μm is preferable, a range of 1 &#12316; 7 μm is more preferable, and a range of 1.2 &#12316; 5 μm is more preferable.

  In the present invention, the content of particles contained in the polyester film is preferably in the range of 0.01 &#12316; 1% by weight from the viewpoints of particle aggregation and transparency, and deterioration of gas barrier properties due to coarse protrusions. Preferably, it is in the range of 0.01 &#12316; 0.5% by weight.

  Further, within a range not impairing the object of the present invention, these polyesters contain a small amount of other polymers, antioxidants, heat stabilizers, antistatic agents, ultraviolet absorbers, plasticizers, pigments or other additives. Etc. may be contained.

  Next, although the manufacturing method of the polyester film used as the base material of this invention is demonstrated, it does not specifically limit to this. The polyester of the present invention is obtained by drying the above-mentioned polyester resin by a normal method, melt-extruding it into a sheet form from a T-shaped base, and making it adhere to a casting drum by an electrostatic application method or the like to cool and solidify to obtain an unstretched polyester sheet. . Next, the obtained unstretched sheet is heated to a glass transition temperature (hereinafter referred to as Tg) or higher and stretched in the longitudinal direction between rolls having a speed difference. Thereafter, the film is heated in the tenter at Tg or more and stretched in the width direction. Subsequently, the biaxially stretched polyester film can be obtained by trimming the ear portion held by the clip through a heat setting treatment, a heat relaxation treatment in the width direction, and a cooling step, and winding it in a roll shape. Then, it slits to the designated vapor deposition processing roll width | variety, and the polyester film roll for vapor deposition is obtained.

  The polyester film serving as the base material of the present invention has a difference of the refractive index Nx in the longitudinal direction and the refractive index Ny in the width direction (Nx−Ny) of −0.030 or more and 0.015 over the entire film width. Or less, more preferably −0.025 or more and 0.010 or less. By making Nx-Ny within the range of -0.030 or more and 0.015 or less, a good orientation balance is obtained, and there is no deformation or wrinkle generation in tension during the vapor deposition process, and a stable vapor deposited thin film is formed. A vapor-deposited polyester film having excellent gas barrier properties can be obtained. Here, the sampling position of the sample in the full width is the center position in the width direction and the position at intervals of 500 mm from the center position toward both ends, and when the 500 mm interval cannot be secured in the vicinity of both ends, the sampling position is the end position that can be collected. . Moreover, paying attention to the maximum value and the minimum value of each measurement position data, both satisfy the said range, and are within the range.

  The polyester film used as the base material of the present invention has a thermal shrinkage of 0.8% or more and 2.0% or less in the longitudinal direction when heat-treated at 150 ° C. for 30 minutes according to the evaluation method described below in the entire film width. It is preferably −0.5% or more and 1.0% or less, more preferably 1.0% or more and 1.8% or less in the longitudinal direction, and −0.3% or more and 0.8% or less in the width direction. . By making the heat shrinkage rate in the longitudinal direction and the width direction within the above range, dimensional stability against heat can be obtained at the time of vapor deposition processing, and there is no deformation or wrinkle due to heat, and a stable vapor deposited thin film is formed. A vapor-deposited polyester film having excellent gas barrier properties can be obtained. Here, the sampling position of the sample in the full width is the center position in the width direction and the position at intervals of 500 mm from the center position toward both ends, and when the 500 mm interval cannot be secured in the vicinity of both ends, the sampling position is the end position that can be collected. . Moreover, paying attention to the maximum value and the minimum value of each measurement position data, both satisfy the said range, and shall be within the range.

  The polyester film serving as the base material of the present invention preferably has an orientation angle change amount of 0 ° or more and 20 ° or less per 1 m, more preferably 0 ° or more and 16 ° with respect to the film width direction. It is 0 ° or less, more preferably 0 ° or more and 12 ° or less. Here, the orientation angle is the inclination of the principal axis of the molecular chain orientation with respect to the width direction. When the amount of change in the orientation angle is larger than 20 ° per meter, the main molecular orientation direction in the vapor deposition processing roll width is greatly different. Therefore, when a wide roll is used, the runnability deteriorates during the vapor deposition processing. It is not preferable because wrinkles are easily generated obliquely, and unevenness or omission of the vapor-deposited thin film partially occurs and the gas barrier properties deteriorate. In addition, when the amount of change in the orientation angle is large, the variation in Nx-Ny in the entire film width is increased, which is not preferable. Here, the sampling position of the sample in the full width is a central position and a position at intervals of 500 mm from the central position toward both ends, and an end position where sampling can be performed when a 500 mm interval cannot be secured in the vicinity of both ends. In addition, it is assumed that the above range is satisfied because the maximum value of each variation obtained from between two adjacent sampling positions is within the range.

  The biaxially stretched polyester film as the base material of the present invention is +45 with the clockwise direction as the positive direction with respect to the longitudinal direction when heat-treated at 150 ° C. for 30 minutes according to the evaluation method described later with respect to the film width direction. It is preferable that the amount of change in the difference between the heat shrinkage rate in the ° direction and the heat shrinkage rate in the -45 ° direction (hereinafter referred to as the oblique heat shrinkage rate difference) is 0% or more and 0.25% or less per meter. Preferably they are 0% or more and 0.20% or less, More preferably, they are 0% or more and 0.15% or less. When the amount of change in the oblique heat shrinkage difference is greater than 0.25% per meter, the shrinkage behavior due to heat within the vapor deposition processing roll width is greatly different. It is not preferable because wrinkles are likely to occur, unevenness or omission of the deposited thin film occurs partially, and gas barrier properties deteriorate. In addition, when the difference in the oblique heat shrinkage rate is large, the variation in the heat shrinkage rate in the longitudinal direction and the width direction in the entire film width is also not preferable. Here, the sampling position of the sample in the full width is a central position and a position at intervals of 500 mm from the central position toward both ends, and an end position where sampling can be performed when a 500 mm interval cannot be secured in the vicinity of both ends. In addition, it is assumed that the above range is satisfied because the maximum value of each variation obtained from between two adjacent sampling positions is within the range.

  Obtaining a biaxially stretched polyester film having the properties of a substrate as an object of the present invention, that is, obtaining an orientation balance and a heat shrinkage rate suitable for vapor deposition processing, while achieving an orientation angle and oblique heat within a wide film roll width. In order to control the amount of change in shrinkage difference within the above range, it can be achieved by appropriately combining the following film forming conditions such as stretching conditions in the longitudinal direction and width direction, heat setting conditions, heat relaxation conditions, etc. Become. This will be described in detail below.

(1) Longitudinal stretching conditions In order to obtain a biaxially stretched polyester film having the characteristics of a base material suitable for the purpose of the present invention, as a stretching method in the longitudinal direction, uniaxially stretched polyester with suppressed longitudinal shrinkage stress is used. It is preferable to obtain a film, whereby the longitudinal stress generated in the next tenter, which is the next step, can be suppressed, so that bowing can be reduced. For example, it is preferable that the stretching temperature is (Tg + 15) to (Tg + 55) ° C., and the stretching ratio is 3.3 to 4.7 times. When the stretching temperature is higher than (Tg + 55) ° C. or lower than 3.3 times, bowing is reduced, and the amount of change in the orientation angle and oblique heat shrinkage difference of the resulting biaxially stretched polyester film is reduced, Since the molecular orientation in the width direction is too large compared to the longitudinal direction, the orientation balance is lost, which is not preferable. Moreover, since the planarity of the obtained biaxially stretched polyester film deteriorates, it is not preferable. On the other hand, when the temperature is lower than (Tg + 15) ° C. or higher than 4.7 times, the shrinkage stress increases and the bowing increases, so the change in the orientation angle and oblique heat shrinkage difference of the obtained biaxially stretched polyester film. Since the amount increases, it is not preferable.

  Moreover, since the neck-in phenomenon which shrink | contracts in the width direction arises until the resin which came out of the T-shaped nozzle | cap | die contacts the casting drum, both ends of an unstretched film become thicker than a center part. Therefore, at the time of stretching in the longitudinal direction, the molecular orientation and shrinkage stress at both ends become higher than the central part, and when the uniaxially stretched film is stretched in the width direction, not only an increase in bowing but also biaxiality obtained. The difference in physical properties between the center and both ends of the stretched polyester film is increased. Therefore, it is preferable to obtain a uniaxially stretched polyester film in which the molecular orientation and shrinkage stress at the end are reduced to reduce the difference in physical properties in the width direction.

  Examples of methods for reducing molecular orientation and shrinkage stress at both ends include, for example, a method in which both ends of a film are heated separately from the central portion, a method in which a tapered roll is used as a nip roll used in stretching in the longitudinal direction, and a plurality of methods. The method of carrying out multistage extending | stretching between rolls etc. is mentioned.

  In the method of heating both ends of the film separately from the central portion, both ends thicker than the central portion are separately heated with an infrared heater or the like to obtain a uniaxially stretched polyester film with reduced molecular orientation and shrinkage stress at both ends. be able to. As temperature conditions, it is a preferable range to heat so that the film temperature of both ends becomes 0-20 degreeC higher than a center part, More preferably, it is the range of 2-15 degreeC. When the temperature is higher than 20 ° C., both end portions are heated and whitened, and breakage occurs during stretching in the width direction, which is not preferable. As a ratio which heats a film both ends, the range of 5-30% is preferable from an edge part with respect to a film full width, and the range of 10-20% is further more preferable.

  A method of using a tapered roll as a nip roll used for stretching in the longitudinal direction is a useful means for making uniform the stretching point in the film width direction during stretching. Generally, in stretching between rolls in the longitudinal direction, a nip roll is provided at the upper part of the roll to fix the stretching point, but because the thickness of both ends is thick due to the neck-in phenomenon, the stretching point in the film width direction should be matched. Is difficult and cannot be uniformly stretched in the film width direction. Therefore, variations in molecular orientation and contraction stress occur in the width direction, and in particular, the molecular orientation and contraction stress at both ends tend to increase. Therefore, by using a nip roll with a tapered part with a narrow roll diameter from the center to both ends, it becomes possible to stretch uniformly in the film width direction, reducing molecular orientation and shrinkage stress at both ends. Can be made.

  Also, in the stretching in the longitudinal direction, in the method of stretching in multiple stages between a plurality of rolls instead of stretching in one stage, since the film is gradually stretched in the longitudinal direction while controlling the stretching speed, Differences in physical properties can be reduced. Two-stage to five-stage stretching is preferable from the viewpoint of effects, equipment, and cost.

(2) Stretching condition in the width direction In order to obtain a biaxially stretched polyester film having the characteristics of a base material suitable for the purpose of the present invention, the stretching method in the width direction is while maintaining an orientation balance suitable for vapor deposition. The conditions for reducing the bowing are preferable. For example, the stretching temperature is preferably (Tg + 15) to (Tg + 60) ° C., and the stretching ratio is preferably 3.5 to 4.7 times. When the stretching temperature is higher than (Tg + 60) ° C. or lower than 3.5 times, the molecular orientation in the longitudinal direction becomes too large as compared with the width direction of the obtained biaxially stretched polyester film, which is not preferable because the orientation balance is lost. Moreover, since the planarity of the obtained biaxially stretched polyester film deteriorates, it is not preferable. On the other hand, when it is lower than (Tg + 15) ° C. or higher than 4.7 times, bowing is reduced, and the amount of change in the orientation angle of the resulting biaxially stretched polyester film is reduced, but the width direction is longer than the longitudinal direction. This is not preferable because the molecular orientation is too large and the alignment balance is lost. In addition, when the molecular orientation in the width direction is too large, the inclination of the orientation angle and the change in distortion of the heat shrinkage rate do not have a proportional relationship, and the amount of change in the orientation angle is reduced. The amount of change in the heat shrinkage difference is rather undesirable because it shows an increasing tendency.

(3) Heat setting conditions In order to obtain a biaxially stretched polyester film having the properties of a base material suitable for the purpose of the present invention, the heat setting method includes heat shrinkage in the longitudinal direction and width direction suitable for vapor deposition. Conditions that suppress the increase in bowing of thermal shrinkage due to high-temperature treatment are preferable. For example, the heat setting temperature is preferably 220 to 245 ° C. When the heat setting temperature is higher than 245 ° C., bowing increases, and the amount of change in the orientation angle and the oblique heat shrinkage difference of the resulting biaxially stretched polyester film increases, which is not preferable. On the other hand, a temperature lower than 220 ° C. is not preferable because the thermal shrinkage rate is increased in both the longitudinal direction and the width direction, and the thermal dimensional stability at the time of vapor deposition is deteriorated.

(4) Thermal Relaxation Conditions In order to obtain a biaxially stretched polyester film having the characteristics of a base material suitable for the purpose of the present invention, as a thermal relaxation method, while achieving a thermal contraction rate in the width direction suitable for vapor deposition processing The condition that restrains the increase in bowing due to the fact that the binding force in the width direction is reduced by the thermal relaxation treatment and is easily deformed is preferable. For example, the thermal relaxation rate in the width direction is preferably 4 to 8%. When the thermal relaxation rate is less than 4%, the resulting biaxially stretched polyester film has a high thermal shrinkage rate in the width direction, which is not preferable because the dimensional stability at the time of vapor deposition is deteriorated. On the other hand, when the thermal relaxation rate is larger than 8%, bowing increases, and the amount of change in the orientation angle and oblique heat shrinkage difference of the resulting biaxially stretched polyester film increases, such being undesirable.

  Also, in the thermal relaxation treatment process, the restraining force in the width direction decreases until the film is shrunk due to thermal relaxation, and the film relaxes due to its own weight, or the film may swell due to the accompanying air flow. The film is in a situation where it tends to fluctuate up and down. For this reason, in this thermal relaxation process, the amount of change in the orientation angle and the oblique heat shrinkage difference of the resulting biaxially stretched polyester film varies greatly depending on the film transport state. As a method of reducing, for example, the film can be kept parallel by appropriately adjusting the wind speed blown from the upper and lower nozzles. As a preferable state of the film, the maximum bulge of the central portion is ± 100 mm or less, more preferably ± 50 mm or less with respect to the surface connecting both ends of the film held by the clip with a straight line. In addition, the swelling to the upper part was set to +, and the swelling to the lower part was set to-.

  The biaxially stretched polyester film serving as the substrate of the present invention preferably has a thickness of 5 to 20 μm, more preferably 8 to 16 μm, from the viewpoint of maintaining mechanical strength and flexibility as a packaging application.

  The biaxially stretched polyester film serving as the substrate of the present invention may be a single layer as a layer structure, A / B two layers, A / B / A or A / B / C three layers, and further three layers The above multilayer structure may be used, and is not particularly limited. Further, the thickness ratio of each layer is not particularly limited. By adopting a multilayer structure, the surface roughness of the surface to be deposited can be controlled, and it can also be used as a means for controlling transparency, such as providing a layer that does not contain particles on one side. For these laminated structures, a lamination method by a coextrusion molding method can be suitably employed.

  The polyester film serving as the base material of the present invention is preferably subjected to corona discharge treatment on at least one surface, and the surface subjected to the corona discharge treatment is preferably the surface on which the deposited layer is laminated. By performing the corona discharge treatment, the adhesion with the vapor deposition layer is improved, and a polyester film having excellent gas barrier properties can be obtained.

  The width of the master roll made of the polyester film serving as the substrate of the present invention is not particularly limited, but is preferably 4000 mm or more, more preferably 5000 mm or more, and still more preferably 6000 mm or more from the viewpoint of productivity. However, since the handling becomes difficult if the width of the master roll is too wide, it is preferably 20000 mm or less.

  The roll width of the polyester film for vapor deposition obtained by slitting the master roll made of the biaxially stretched polyester film as the substrate of the present invention is not particularly limited, but is preferably 1500 mm or more from the viewpoint of productivity. Is 1750 mm or more, more preferably 2000 mm or more. However, if the width of the slit roll is too wide, handling becomes difficult.

  Examples of the thin film to be deposited on the biaxially stretched polyester film serving as the base material of the present invention include metals and metal oxides. From the viewpoints of oxygen and water vapor barrier properties, productivity, and transparency, aluminum oxide, silicon oxide or the like Mixtures are preferred.

The vapor-deposited polyester film obtained in the present invention preferably has an oxygen permeation amount of 20 ml / m ² · day · MPa or less from the viewpoint of maintaining the quality of the contents when used as a packaging material.

The vapor-deposited polyester film obtained by the present invention preferably has a water vapor transmission rate of 2.0 g / m ² / day or less from the viewpoint of quality retention of the contents when used as a packaging material.

  The present invention will be specifically described below with reference to examples. In addition, this invention is not limited to the Example described below. In addition, each evaluation item in an Example and a comparative example was measured with the following method.

(1) Intrinsic viscosity [η]
It melt | dissolved in the mixed solvent of phenol / tetrachloroethane = 60/40 (weight ratio), and measured at 30 degreeC using the Ostwald viscometer. In addition, the measurement was performed 3 times and the average value was obtained.

(2) Glass transition temperature (Tg)
Using a differential scanning calorimeter (DSC 6220, manufactured by SII Nanotechnology Inc.), the sample was melted to 280 ° C. in a nitrogen atmosphere, held for 5 minutes, rapidly cooled with liquid nitrogen, and then raised from room temperature. The measurement was carried out at a temperature rate of 20 ° C./min.

(3) Refractive index Using the sodium D line (wavelength 589 nm) as a light source, the refractive index (Nx, Ny) in the longitudinal direction and the width direction was measured using an Abbe refractometer, and (Nx−Ny) was calculated and obtained. . In addition, the measurement was performed at intervals of 500 mm toward the both ends from the center and the center position with respect to the obtained biaxially stretched film roll width. Moreover, when 500 mm space | interval was not securable in the both ends vicinity, it measured in the end position which can be measured. With respect to Nx-Ny obtained in this way, the maximum value and the minimum value of Nx-Ny in the entire roll width were obtained.

(4) Thermal contraction rate in the longitudinal direction and the width direction The sample was cut to a width of 10 mm and a length of 250 mm in the longitudinal direction and the width direction, marked at intervals of 200 mm, and the spacing between the marks under a constant tension of 5 gf (A) Measure. Next, the film was heat-treated at 150 ° C. for 30 minutes under no load, and then the mark interval (B) was measured under a constant tension of 5 gf, and the thermal shrinkage rate was obtained from the formula (1). In addition, the measurement was performed at intervals of 500 mm toward the both ends from the center and the center position with respect to the obtained biaxially stretched film roll width. Moreover, when 500 mm space | interval was not securable in the both ends vicinity, it measured in the end position which can be measured. The maximum value and the minimum value of the heat shrinkage rate in the longitudinal direction and the width direction in the entire width of the roll were obtained with respect to the heat shrinkage rate thus obtained.
Thermal contraction rate (%) = {(A−B) / A} × 100 Formula (1)

(5) Change in oblique heat shrinkage difference with respect to film width direction First, with respect to the longitudinal axis as a reference, the clockwise direction is the positive direction and the sample is 10 mm wide and 250 mm long in the + 45 ° direction and the −45 ° direction. The heat shrinkage rate with respect to the + 45 ° direction and the −45 ° direction was determined in the same manner as in the above method, and the oblique heat shrinkage rate difference was determined from Equation (2). In addition, the measurement is performed at intervals of 500 mm from the center and the center position toward the both ends with respect to the obtained full width of the biaxially stretched film roll, and the amount of change in the oblique heat shrinkage difference between the two adjacent points. Was calculated per 1 m from the formula (3). Moreover, when 500 mm space | interval was not securable in the both ends vicinity, it measured in the end position which can be measured, it divided by the distance of the measured sample space | interval, and converted similarly per 1m.
Diagonal difference in heat shrinkage rate (%) = heat shrinkage rate (+ 45 ° direction) −heat shrinkage rate (−45 ° direction)
Formula (2)
Change in oblique heat shrinkage difference per meter (% / m)
= | Differential heat shrinkage rate difference between two adjacent points (%) | ÷ 500 (mm) × 1000 (mm / m) Equation (3)
And the maximum value of a plurality of change amounts between the two adjacent sampling positions calculated was used as the change evaluation result of the film.
Here, according to the equation (2), the data of the diagonal difference (%) of the heat shrinkage rate may be positive data or negative data. Then, in Equation 3, if the absolute value of the difference in oblique heat shrinkage rate (%) between two adjacent points is calculated, which one of the oblique difference (%) in the heat shrinkage rate at the sampling positions of the two adjacent points? The same positive value can be obtained by subtracting, and the change amount (% / m) of the difference in oblique heat shrinkage per 1 m can be calculated regardless of which is subtracted from either.

(6) Amount of change in orientation angle in the film width direction The film is cut into 100 mm × 100 mm, and a molecular chain is measured on the axis in the width direction of the film using a MOA-6004 type molecular orientation meter manufactured by Oji Scientific Co., Ltd. The orientation angle of the main axis was determined. At this time, the counterclockwise inclination with respect to the film width direction was defined as +, and the clockwise direction as −. In addition, the measurement is performed at intervals of 500 mm toward the both ends from the center and the center position with respect to the obtained biaxially stretched film roll width, and the amount of change in the orientation angle between each two adjacent points is obtained. The value was converted per 1 m from the formula (4). Moreover, when 500 mm space | interval was not securable in the both ends vicinity, it measured in the end position which can be measured, it divided by the distance of the measured sample space | interval, and converted similarly per 1m.
Change in orientation angle per meter (° / m)
= | Difference in orientation angle between two adjacent points (°) | ÷ 500 (mm) × 1000 (mm / m) Equation (4)
And the maximum value of a plurality of change amounts between the two adjacent sampling positions calculated was used as the change evaluation result of the film.

(7) Oxygen transmission rate The oxygen transmission rate was measured under the conditions of a temperature of 23 ° C. and a humidity of 65% using an oxygen transmission rate measuring device (OX-TRAN100 manufactured by Modern Controls) and evaluated as follows. .
A: 0 or more and less than 20 (ml / m ² · day · MPa) ○: 20 or more and less than 40 (ml / m ² · day · MPa) ×: 40 (ml / m ² · day · MPa) or more

(8) Water vapor transmission rate The water vapor transmission rate was measured under the conditions of a temperature of 40 ° C and a humidity of 90% using a water vapor transmission rate measuring device (PERMATRAN-W manufactured by Modern Controls) and evaluated as follows. .
A: 0 or more and less than 2 (g / m ² · day) ○: 2 or more and less than 4 (g / m ² · day) ×: 4 (g / m ² · day) or more

(9) Workability and Appearance Evaluation The film workability during vapor deposition and the appearance evaluation after processing were evaluated with ○ and ×. If there was no sagging or wrinkles and the running performance was good, it was rated as “Good”.

[Example 1]
Polyethylene terephthalate (intrinsic viscosity = 0.62 dl / g, Tg = 78 ° C.) containing 0.1% by weight of silica having an average particle size of 2.5 μm is dried and then fed to an extruder and melted at 285 ° C. And discharged from a T-shaped base and cooled and solidified with a casting drum to obtain an unstretched polyethylene terephthalate sheet. This sheet was heated to 115 ° C., and stretched in the longitudinal direction at a total stretching ratio of 4.0 times by two-stage stretching in which the first stage was 1.4 times and the second stage was 2.86 times. At this time, an infrared heater was installed at a position of 10% from both ends with respect to the full width of the unstretched sheet, and the film temperature at the end rather than the center was set to + 3 ° C. Subsequently, the film was stretched in the width direction at a temperature of 115 ° C. and a stretch ratio of 4.3 times, heat-fixed at 235 ° C., and heat-relaxed by 5% in the width direction. At this time, the bulge at the center of the film in the heat relaxation zone was adjusted to +50 mm by adjusting the nozzle air volume at the top and bottom. And the ear | edge part was trimmed and the master roll of the biaxially-stretched polyethylene terephthalate film of thickness 12 micrometers and roll width 6300mm was obtained by winding in roll shape through a corona discharge process. The obtained film was measured for refractive index, thermal shrinkage, and orientation angle. Moreover, the obtained master roll was slit to each 2200 mm width, and the film roll for vapor deposition processing was obtained. An inorganic oxide layer of aluminum oxide was formed as an inorganic thin film layer on the corona-treated surface of the film roll for vapor deposition processing obtained above by an electron beam vapor deposition method. A particulate Al ₂ O ₃ (purity: 99.9%) having a size of about 3 to 5 mm is used as a deposition source, an electron gun is used as a heating source, the supply of oxygen gas is adjusted, and the degree of vacuum is 10 ^-4 Deposition was performed under the condition of Torr or less. The film thickness of the obtained aluminum oxide thin film layer was 20 nm. Oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Example 2]
As stretching conditions in the longitudinal direction, the temperature is 105 ° C., the first stage is 1.3 times, the second stage is 2.77 times, the total stretching ratio is 3.6 times, and the film temperature at the end is higher than the center part. + 2 ° C., except that the stretching conditions in the width direction were changed so that the temperature was 118 ° C., the stretching ratio was 4.5 times, the heat setting temperature was 230 ° C., and the bulge at the center of the film in the thermal relaxation zone was 0 mm. A biaxially stretched polyethylene terephthalate film having a thickness of 15 μm was obtained in the same manner as in Example 1. In the same manner as in Example 1, slitting and aluminum oxide vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Example 3]
Polyethylene terephthalate (A) (intrinsic viscosity = 0.62 dl / g, Tg = 78 ° C.) containing 0.14% by weight of silica having an average particle size of 2.5 μm and silica having an average particle size of 2.5 μm were reduced to 0.0. Polyethylene terephthalate (B) contained at 035% by weight (intrinsic viscosity = 0.62 dl / g, Tg = 78 ° C.) was dried and then fed to a separate extruder, melted at 285 ° C., and A / B / A After joining so as to form a seed three-layer structure, it was discharged from a T-shaped base and cooled and solidified with a casting drum to obtain an unstretched polyethylene terephthalate sheet. At this time, the discharge amount was adjusted so that the thickness ratio of each layer was A / B / A = 7/86/7.

  Using this sheet, as the stretching conditions in the longitudinal direction, the temperature was 116 ° C., the first stage was 1.5 times, the second stage was 2.85 times, and the total stretching ratio was 4.3 times. Is set to + 4 ° C. from the central portion, and the stretching conditions in the width direction are as follows: the temperature is 112 ° C., the stretching ratio is 4.2 times, the heat setting temperature is 235 ° C., and the thermal relaxation treatment is performed in the width direction by 4%. The biaxially stretched polyethylene terephthalate film was obtained in the same manner as in Example 1 except that the bulge was +50 mm. In the same manner as in Example 1, slitting and aluminum oxide vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Example 4]
As stretching conditions in the longitudinal direction, the temperature is 110 ° C., the first stage is 1.3 times, the second stage is 3.0 times, the total stretching ratio is 3.9 times, and the film temperature at the end is higher than that at the center. A biaxially stretched polyethylene terephthalate film having a thickness of 9 μm was obtained in the same manner as in Example 1 except that the temperature was + 3 ° C., the heat setting temperature was 225 ° C., and the heat relaxation treatment was changed in the width direction by 6%. In the same manner as in Example 1, slitting and aluminum oxide vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Example 5]
Using the film roll for vapor deposition processing obtained by the method of Example 1, an inorganic oxide layer of silicon dioxide was formed on the corona-treated surface as an inorganic vapor deposition layer by an electron beam vapor deposition method. Supply of oxygen gas by using particulate Si (purity 99.99%) and SiO ₂ (purity 99.9%) having a size of about 3 to 5 mm as a deposition source, using an electron gun as a heating source Were adjusted, and vapor deposition was performed under a condition of a degree of vacuum of 10 ⁻⁴ Torr or less. The film thickness of the obtained silicon dioxide thin film layer was 20 nm. Oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Example 6]
Using the film roll for vapor deposition processing obtained by the method of Example 1, a composite inorganic oxide layer of silicon dioxide and aluminum oxide was formed as an inorganic vapor deposition layer on the corona-treated surface by an electron beam vapor deposition method. As the evaporation source, particulate SiO ₂ (purity 99.9%) and A1 ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm were used. Here, the composition of the composite oxide layer was SiO ₂ / A1 ₂ O ₃ (mass ratio) = 60/40. An electron gun was used as a heating source, and vapor deposition was performed under conditions of a degree of vacuum of 10 ⁻⁴ Torr or less. The film thickness of the obtained silicon dioxide and aluminum oxide thin film layer was 20 nm. Oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Comparative Example 1]
As the stretching conditions in the longitudinal direction, the first stage is 1.6 times, the second stage is 3.1 times, and the total stretching ratio is 4.9 times, and the end portion is not heated (the end portion is more than the center portion). (The film temperature was −3 ° C.), 10% heat relaxation treatment was performed in the width direction, and the nozzle air volume at the upper and lower portions of the heat relaxation zone was not adjusted (the swelling at the center of the film was +150 mm), otherwise Obtained a biaxially stretched polyethylene terephthalate film in the same manner as in Example 1. Similarly, slitting and vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Comparative Example 2]
As the stretching conditions in the longitudinal direction, the first stage is 1.3 times, the second stage is 2.92 times, the total stretch ratio is 3.8 times, and the end portion is not heated (the end portion is more than the center portion). The film temperature was −3 ° C.) As the stretching conditions in the width direction, the temperature was 118 ° C., the stretching ratio was 4.8 times, the heat setting temperature was 248 ° C., and the heat relaxation treatment was 5% in the width direction. No adjustment was made on the upper and lower nozzle airflow (the bulge at the center of the film was +150 mm). Otherwise, a biaxially stretched polyethylene terephthalate film having a thickness of 15 μm was obtained in the same manner as in Example 1. Similarly, slitting and vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

[Comparative Example 3]
The heat setting temperature is 190 ° C., 2% thermal relaxation treatment in the width direction, and the nozzle air volume at the upper and lower portions of the thermal relaxation zone is not adjusted (the bulge at the center of the film was +120 mm). In the same manner, a biaxially stretched polyethylene terephthalate film having a thickness of 9 μm was obtained. Similarly, slitting and vapor deposition were performed, and oxygen and water vapor transmission rates were measured. The results are shown in Table 1.

  The film for vapor deposition using the biaxially stretched polyethylene terephthalate film obtained from the examples as a base material was excellent in vapor deposition processability, and a gas barrier film excellent in oxygen and water vapor barrier properties was obtained. On the other hand, the film for vapor deposition using the biaxially stretched polyethylene terephthalate film obtained from Comparative Examples 1 to 3 as a base material has poor wrinkle generation and running property during vapor deposition processing, and the obtained film has oxygen and water vapor gas barriers. It was inferior in nature.

  ADVANTAGE OF THE INVENTION According to this invention, the vapor deposition polyester film excellent in the productivity in a vapor deposition process and excellent in oxygen and water vapor | steam gas barrier property can be provided.

Claims (6)

A vapor-deposited polyester film having a vapor-deposition layer on at least one side of a biaxially stretched polyester film having a thickness of 5 to 20 μm, having an oxygen transmission rate of 20 ml / m ² · day · MPa or less and a water vapor transmission rate of 2.0 g / A vapor-deposited polyester film characterized in that it is m ² / day or less and the biaxially stretched polyester film satisfies all of the following requirements (1) to (4).
(1) In the full width of the film, the difference (Nx−Ny) between the refractive index Nx in the longitudinal direction and the refractive index Ny in the width direction is within a range of −0.030 or more and 0.015 or less. The heat shrinkage rate when heat-treated at 150 ° C. for 30 minutes is in the range of 0.8% to 2.0% in the longitudinal direction and −0.5% to 1.0% in the width direction (3 ) The amount of change in the orientation angle with respect to the film width direction is 0 ° or more and 20 ° or less per meter. (4) When heat treated at 150 ° C. for 30 minutes with respect to the film width direction, The amount of change in the film width direction of the difference between the heat shrinkage rate in the + 45 ° direction and the heat shrinkage rate in the −45 ° direction (diagonal heat shrinkage rate difference) with the clockwise direction as the positive direction is 0% or more and 0.25% per meter. Here, in the requirements (1) to (4) Sampling position of the fee, and the position of the intervals of 500mm toward both ends from the center position and a central position with respect to the entire width, when it is not possible to secure the 500mm spacing in the vicinity of both ends, and harvestable end position.
In the requirements (1) and (2), the maximum value and the minimum value of each measurement position data are within the range, and the requirements (3) and (4) are each change amount between two adjacent sampling positions. It is a requirement that the maximum value of is within the range.   The vapor deposition polyester film according to claim 1, wherein the vapor deposition layer is made of a metal or a metal oxide.   The vapor-deposited polyester film according to claim 1 or 2, wherein the vapor-deposited layer is made of a metal oxide, and the metal oxide is made of aluminum oxide, silicon oxide, or a mixture thereof.   The film full width is 1500 mm or more, The vapor deposition polyester film of any one of Claims 1-3 characterized by the above-mentioned.   The vapor-deposited polyester film according to claim 1, wherein particles are contained in the biaxially stretched polyester film.   It is a manufacturing method of the vapor deposition polyester film in any one of Claims 1-5, Comprising: At least single side | surface of the said biaxially stretched polyester film is subjected to a corona discharge treatment, and the film surface subjected to the corona discharge treatment is subjected to a vacuum vapor deposition method. A method for producing a vapor-deposited polyester film, comprising depositing a vapor-deposited layer by any one of a sputtering method and an ion beam method.