CN107405908B - Laminated film and method for producing the same - Google Patents

Abstract

The present invention provides a laminated film that has various functions as a laminated film, has high mechanical strength, and can be processed with high yield and high precision in various processing steps. The laminated film of the present invention is characterized in that it is a laminated film formed by alternately laminating a total of 11 or more layers of a layer A formed of a crystalline polyester and a layer B formed of a thermoplastic resin different from the above-mentioned crystalline polyester, wherein the above-mentioned The Young's modulus in the orientation axis direction of the laminated film (the direction in which the Young's modulus is the largest) is 6 GPa or more.

Description

Laminated film and method for producing the same

technical field

The present invention relates to a laminated film and a method for producing the same.

Background technique

Thermoplastic resin films, especially biaxially stretched polyester films, have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency, and chemical resistance. Therefore, they are widely used in magnetic recording materials, packaging materials, etc. It is widely used as a base film in various applications such as.

On the other hand, as a polyester film, a laminated film in which different resins are alternately laminated is used. Such a laminated film can be a film having a special function that cannot be obtained by a single-layer film, for example, a tear-resistant film having improved tear strength (refer to Patent Document 1), An infrared reflective film that reflects infrared rays (refer to Patent Document 2.), a polarized light reflective film having polarized light reflection properties (refer to Patent Document 3.), and the like.

However, since the above-mentioned laminated film has a structure in which different resins are alternately laminated, compared with a single-layer film, the mechanical strength and dimensional stability tend to be lowered due to the influence of the lamination thickness. If the mechanical strength and dimensional stability of the laminated film decrease, for example, when combined with various other films and members, and subjected to processing such as punching, cutting, coating, and lamination to form a functional film, the film may be damaged by the force applied to the film. Deformation, breakage, etc. of the film are caused, and there are problems such as reduction in processing accuracy and yield at the time of processing, and deterioration in optical properties and quality of the obtained film, or dimensional changes when actually mounted on a product or the like. associated adverse events.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent No. 3960194

Patent Document 2: Japanese Patent No. 4310312

Patent Document 3: Japanese Patent Laid-Open No. 2014-124845

SUMMARY OF THE INVENTION

The problem to be solved by the invention

Therefore, an object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a film having various functions as a laminated film, high mechanical strength, dimensional stability, and high yield in various processing steps. , Laminated film that is processed with high precision and does not cause problems in actual use.

means of solving problems

The present invention was made in order to solve the above-mentioned problems, and the laminated film of the present invention is characterized in that an A layer formed of a crystalline polyester and a B layer formed of a thermoplastic resin different from the crystalline polyester described above are alternately laminated. A total of 11 or more laminated films have a Young's modulus of 6 GPa or more in the orientation axis direction of the laminated film (the direction in which the Young's modulus is the largest).

According to a preferred embodiment of the laminated film of the present invention, in the above-mentioned laminated film, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1390 cm ⁻¹ , the peak intensity I max in the direction of maximum reflectance is perpendicular to the polarization Raman spectrum. The ratio I max/I min of the peak intensity I min in the direction of 5 is 5 or more.

According to a preferable aspect of the laminated film of this invention, 90 mol% or more of naphthalenedicarboxylic acid is contained in the carboxylic acid component which comprises the said crystalline polyester.

According to a preferred embodiment of the laminated film of the present invention, the absolute value of the coefficient of linear expansion at a temperature of 40° C. or higher and 50° C. or lower in any of the orientation axis direction of the laminate film and the direction perpendicular to the orientation axis direction. 10ppm/°C or less.

According to a preferred embodiment of the laminated film of the present invention, the reflectance when the incident angle of the polarized light component parallel to the incident plane including the orientation axis direction of the laminated film is 10° is denoted as R1, and the reflectance with respect to the above-mentioned including When the incident angle of the polarized light component perpendicular to the incident plane in the orientation axis direction is 10°, the reflectance at a wavelength of 550 nm satisfies the following equations (2) and (3) when the reflectance is denoted as R2.

·R2(550)≤40%...(2)

·R1(550)≥70%...(3)

According to a preferable aspect of the laminated film of the present invention, in the first temperature rise curve obtained by differential scanning calorimetry (hereinafter referred to as DSC) of the laminated film, the laminated film has a melting peak, and the melting peak has a peak top When the temperature is expressed as Tm, it has an exothermic peak in the range of Tm-110°C or higher and Tm-60°C or lower.

According to a preferable aspect of the laminated film of this invention, the ratio of the Young's modulus of the orientation axis direction of the said laminated film to the direction perpendicular|vertical in the same plane as the orientation axis direction is 2 or more.

According to a preferable aspect of the laminated film of this invention, the thermal shrinkage stress at the temperature of 100 degreeC of the orientation axis direction of the said laminated film is 1 MPa or less.

According to a preferable aspect of the laminated film of this invention, the absolute value of TMA at the temperature of 100 degreeC of the orientation axis direction of the said laminated film is 0.5 % or less.

According to a preferable aspect of the laminated film of this invention, the melting peak derived from the said thermoplastic resin B measured by the differential scanning calorimetry (DSC) of the said laminated film is 5 J/g or less.

According to a preferable aspect of the laminated film of this invention, the said A layer and the said B layer satisfy|fill the following conditions.

A layer: formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, 80 to 100 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, the diol 80-100 mol% of components are ethylene glycol in 100 mol%.

Layer B: It is formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, and 40 to 75 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, 25 to 60 mol % is at least one component selected from isophthalic acid, 1,8-naphthalenedicarboxylic acid, and 2,3-naphthalenedicarboxylic acid, and 80 to 100 mol% of the diol component in 100 mol% is ethylene glycol.

According to a preferred aspect of the laminated film of the present invention, the laminated film can be wound along the orientation axis of the laminated film to form a film roll.

According to a preferable aspect of the film roll of this invention, the width|variety of the said laminated film is 1000 mm or more.

The method for producing a laminated film of the present invention is characterized in that a total of 11 or more layers in total are alternately laminated with respect to the unstretched layer in which the A layer made of crystalline polyester and the B layer made of a thermoplastic resin different from the crystalline polyester are alternately laminated. The film is stretched in the longitudinal direction of the film at a magnification of 2 to 5 times, then stretched in the width direction of the film at a magnification of 2 to 5 times, and further stretched in the longitudinal direction of the film at a magnification of 1.3 to 4 times.

effect of invention

According to the present invention, a laminated film having high mechanical strength and dimensional stability can be obtained, which can be processed or used as various functional films such as punching, cutting, coating, lamination, etc. It can be used properly and can be used without problems during actual installation.

Since the laminated film of the present invention is a laminated film having a high Young's modulus, it is suitable for use in various optical films, engineering films, and the like.

Detailed ways

Next, the laminated film of this invention and its manufacturing method are demonstrated in detail.

The laminated film of the present invention is a layer (layer A) formed of crystalline polyester (hereinafter, sometimes referred to as crystalline polyester A.) and a thermoplastic resin (hereinafter, sometimes referred to as crystalline polyester) different from the aforementioned crystalline polyester. The layer (B layer) formed of thermoplastic resin B.) is alternately laminated with a total of 11 or more laminated films formed.

Here, the crystalline polyester A specifically refers to a polyester that is measured by differential scanning calorimetry (hereinafter, referred to as DSC in some cases) in accordance with JIS K7122 (1999) at a heating rate of 20°C/min. The resin was heated from 25°C to a temperature of 300°C (1st RUN), kept in this state for 5 minutes, then quenched to a temperature of 25°C or lower, and again from 25°C at a temperature increase rate of 20°C/min The temperature was raised to 300°C, and in the obtained differential scanning calorimetry chart of 2ndRUN, the crystal fusion heat ΔHm obtained from the peak area of the melting peak was 15 J/g or more. The crystal fusion heat is more preferably 20 J/g or more, and still more preferably 25 J/g or more.

In addition, the thermoplastic resin B is a thermoplastic resin that exhibits optical properties or thermal properties different from those of the crystalline polyester A used in the A layer. Specifically, it refers to a thermoplastic resin whose refractive index differs by 0.01 or more in any of two vertical directions arbitrarily selected in the plane of the laminated film and a direction perpendicular to the plane, or a thermoplastic resin that exhibits a difference in refractive index with a crystalline polymer in DSC by 0.01 or more. Ester A Thermoplastic polyesters with different melting points and glass transition temperatures.

In addition, the "alternate lamination" here means that the A layer and the B layer are laminated in a regular arrangement in the thickness direction. For example, they are stacked in a regular arrangement represented by A(BA)n (n is a natural number). By alternately stacking resins having different optical properties as described above, interference reflection capable of reflecting light of a wavelength designed by the relationship between the difference in refractive index of each layer and the layer thickness can be exhibited.

In addition, by alternately laminating resins with different thermal properties, it becomes possible to highly control the orientation state of each layer when producing a biaxially stretched film, and to control optical properties, mechanical properties, and thermal shrinkage properties.

Preferable lamination forms of the laminated film include a layer A composed of a crystalline polyester A, a layer B composed of a thermoplastic resin B different from the crystalline polyester A, and a layer composed of a thermoplastic resin B different from the crystalline polyester A. In the case of the C layer formed of the thermoplastic resin C in which the ester A and the thermoplastic resin B are different. In this case, layers C such as CA(BA)n, CA(BA)nC, and A(BA)nCA(BA)m can be laminated on the outermost layer or the intermediate layer.

In addition, when the number of layers to be laminated is less than 11 layers, the lamination of different thermoplastic resins affects various physical properties such as film formability and mechanical properties. For example, it may become difficult to manufacture a biaxially stretched film, and it may be combined with other components. When finished products, defects may occur.

On the other hand, in the case of a laminated film formed by alternately laminating a total of 11 or more layers as in the laminated film of the present invention, each thermoplastic resin can be uniformly disposed compared to a laminated film having less than 11 layers. Therefore, film formability and mechanical properties can be stabilized. In addition, as the number of layers increases, the growth of orientation in each layer tends to be suppressed. For example, as the tear strength due to surface tension increases, it becomes easier to control mechanical properties and thermal shrinkage properties. , it becomes possible to impart special optical properties such as interference reflection function. The number of layers to be stacked is preferably 100 or more, and more preferably 200 or more. For the film, when 100 or more layers are stacked, it is possible to reflect light in a wide area with high reflectivity, and when 200 or more layers are stacked, for example, substantially all visible light with wavelengths of 400 to 700 nm can be reflected. In addition, there is no upper limit on the number of layers to be stacked, but as the number of layers increases, it may cause an increase in manufacturing cost due to an increase in the size and complexity of the manufacturing apparatus. Therefore, in practice, 10,000 layers or less is a practical range.

In the laminated film of the present invention, the Young's modulus in the orientation axis direction of the laminated film needs to be 6 GPa or more. The orientation axis direction of the laminated film here means the direction in which the Young's modulus of the film is measured by changing the direction at every 10° in the film surface, and this Young's modulus becomes the largest. Young's modulus is an index indicating the force required for initial deformation of the film. By making the Young's modulus high, it is possible to use it as a functional film even in processing steps such as punching, cutting, coating, lamination, etc. Even when a force is applied to the laminated film, deformation can be suppressed, and it becomes easy to suppress the processing failure and performance change during use due to the deformation of the film.

The Young's modulus in the orientation axis direction of the laminated film is preferably 8 GPa or more, and more preferably 10 GPa or more. As the Young's modulus increases, the laminated film becomes less deformable, and the control range of processing conditions during processing such as punching, cutting, coating, and lamination becomes wider. Therefore, it is possible not only to suppress processing defects, but also to improve the The properties of the resulting article are also useful. In order to improve the Young's modulus, as will be described later, in addition to the selection of the resin, it is achieved by the method for producing the film.

In addition, in the case of a single layer or several layers, when the Young's modulus of the laminated film in the direction of the orientation axis is 6 GPa or more, the laminated film tends to become brittle due to the orientation strength of the resin, and the handleability is also poor. may decline.

On the other hand, as in the present invention, in the case of a laminated film in which a total of 11 or more layers in total are alternately laminated between the A layer composed of the crystalline polyester A and the B layer composed of the thermoplastic resin B different from the crystalline polyester A. Even if the Young's modulus is 6GPa or more, due to the interfacial tension at the lamination interface or the buffering effect of the B layer formed of the thermoplastic resin B, the Young's modulus can be increased without impairing the workability, and even in punching The effect of suppressing deformation can also be obtained when a force is applied to the laminated film during processing steps such as cutting, coating, and lamination, or when used as a functional film.

Moreover, in the laminated film of this invention, it is also a preferable aspect that the ratio of the orientation axis direction of a laminated film and the Young's modulus of the direction perpendicular|vertical in the same plane is 2 or more. When it is desired to increase the ratio of Young's modulus simply by the selection of the resin and the method for producing the film, the Young's modulus of the laminated film having an equal Young's modulus in the in-plane direction of the laminated film is required. There is a limit to the amount. This is because the Young's modulus depends on the strength of the orientation of the resin constituting the laminated film, and thus the magnitude of the Young's modulus is affected by the degree of strong orientation in the direction in which the Young's modulus is to be increased.

On the other hand, in processing steps such as punching, cutting, coating, and lamination, especially in the step of continuous processing using a roll-shaped film, the improvement of the Young's modulus in the longitudinal direction of the laminated film is required to stabilize the processing step. It's effective. Therefore, by setting the ratio of the orientation axis direction of the laminated film to the Young's modulus in the direction perpendicular to the same plane as 2 or more, the Young's modulus on the orientation axis side can be further improved, and the direction in which the Young's modulus is the largest can be further improved. It becomes easy for the Young's modulus (in the direction of the orientation axis of the laminated film) to be 6 GPa or more. More preferably, the ratio of the orientation axis direction of the laminated film to the Young's modulus of the direction perpendicular to the same plane is 3 or more. In this case, the Young's modulus of the orientation axis direction of the laminated film becomes 10 GPa or more. easy.

For the laminated film of the present invention, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1390 cm ⁻¹ , the ratio of the peak intensity I max in the direction where the reflectance is the largest to the peak intensity I min in the direction perpendicular thereto I max/I min is preferably 5 or more. The direction in which the reflectance is the largest here means that the polarized light component is measured at 0° with respect to the incident surface of the laminated film, and the incident angle is set to 0°, and the direction is changed every 10° in the laminated film surface. In the case of reflectance, the reflectance shows the direction of the maximum value.

In addition, the peak with a wavelength of 1390 cm ⁻¹ observed in the polarized Raman spectrum belongs to the CNC stretching band of the naphthalene ring, and the peak intensity I max in the direction with the highest reflectance and the peak intensity I min in the direction perpendicular to it can be determined. The ratio of Imax/Imin was used to measure the orientation state of the naphthalene ring. I max/I min at a wavelength of 1390 cm ⁻¹ is preferably 5.5 or more, and more preferably 6 or more.

When I max/I min at a wavelength of 1390 cm ⁻¹ is 5 or more, it means that the naphthalene rings are uniformly oriented, and as a result, the Young's modulus can be increased by increasing the orientation. As for the upper limit of I max/I min at a wavelength of 1390 cm ⁻¹ , from preventing the formation of layer A formed of crystalline polyester A containing naphthalene dicarboxylic acid and thermoplastic resin B different from crystalline polyester A from forming The upper limit is preferably 20, more preferably 10, and particularly preferably 7 or less, from the viewpoint of deterioration of the interlayer adhesion due to a large difference in the orientation state and crystallinity of the B layer. The I max/I min at a wavelength of 1390 cm ⁻¹ can be adjusted by the selection of the resin combination of the A layer and the B layer and the film forming conditions.

In addition, in the laminated film of the present invention, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1615 cm ⁻¹ , the ratio of the peak intensity I max in the direction where the reflectance is the largest to the peak intensity I min in the direction perpendicular thereto It is a preferable mode that I max/I min is 4 or more.

The peak of wavelength 1615 cm ⁻¹ observed in the polarized Raman spectrum belongs to the C=C stretching band of the benzene ring, and can be obtained by the sum of the peak intensity I max in the direction with the highest reflectance and the peak intensity I min in the direction perpendicular to it. The ratio of Imax/Imin is used to measure the orientation state of the benzene ring. I max/I min at a wavelength of 1615 cm ⁻¹ is preferably 4.5 or more, and more preferably 5 or more. When I max/I min at a wavelength of 1615 cm ⁻¹ is 4 or more, it means that the benzene rings are uniformly oriented, and as a result, the Young's modulus can be increased by increasing the orientation.

As for the upper limit of I max/I min at a wavelength of 1615 cm ⁻¹ , from preventing the formation of layer A formed by the crystalline polyester A containing naphthalene dicarboxylic acid and the thermoplastic resin B different from the crystalline polyester A from forming The upper limit is preferably 20 or less, more preferably 10 or less, and particularly preferably 6 or less, from the viewpoint of deterioration of interlayer adhesion due to a large difference in the orientation state and crystallinity of the B layer. The I max/I min at the wavelength of 1615 cm ⁻¹ can be adjusted by the selection of the resin combination of the A layer and the B layer and the film forming conditions. Examples of the optimum combination thereof are as described above.

In addition, in the laminated film of the present invention, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1390 cm ⁻¹ , the ratio of the peak intensity I max in the direction where the reflectance is the largest to the peak intensity I min in the direction perpendicular thereto I max/I min is preferably 5 or more.

In the laminated film of the present invention, the absolute value of the linear expansion coefficient at a temperature of 40° C. to 50° C. needs to be 10 ppm/° C. the following. The linear expansion coefficient is an index indicating the ease of change in the size of the film when the temperature is changed. By reducing the absolute value of the thermal expansion coefficient, it is When the functional film is used, even when the temperature of the laminated film changes, deformation of the film can be suppressed, and processing defects accompanying the deformation of the film and changes in performance during use can be easily suppressed.

It is preferable that the absolute value of the linear expansion coefficient is 5 ppm/°C or less in any of the orientation axis direction of the laminated film and the direction perpendicular to the orientation axis direction of the laminated film. As the absolute value of the thermal expansion coefficient decreases, the deformation of the laminated film with respect to the temperature change becomes smaller, for example, the control range of the processing conditions during processing becomes wider. Therefore, not only processing defects can be suppressed, but also the performance of the obtained product can be improved. , or it is useful to suppress dimensional deformation in actual use. In order to reduce the absolute value of the thermal expansion coefficient, as will be described later, in addition to the selection of the resin, it is achieved by the method of manufacturing the laminated film.

In addition, in the case of a single layer or several layers, the absolute value of the linear expansion coefficient at a temperature of 40°C to 50°C in the orientation axis direction of the laminated film is 10 ppm/°C or less, due to the orientation of the resin. In terms of strength, the film tends to become brittle, and the handleability may also decrease. On the other hand, as in the present invention, a laminate film formed by alternately laminating a total of 11 or more layers in the layer A composed of the crystalline polyester A and the layer B composed of the thermoplastic resin B different from the crystalline polyester A described above is alternately laminated. In this case, even if the absolute value of the linear expansion coefficient at a temperature of 40°C to 50°C is 10 ppm/°C or less, the interfacial tension at the lamination interface and the buffering effect of the B layer formed of the thermoplastic resin B do not impair the operation. The coefficient of linear expansion can be significantly reduced, and the effect of suppressing deformation can be obtained even when force is applied to the laminated film during processing steps such as punching, cutting, coating, and lamination, or when used as a functional film.

Moreover, in the laminated film of this invention, it is also a preferable aspect that the thermal shrinkage stress at a temperature of 100° C. in the orientation axis direction of the laminated film is 1 MPa or less. The thermal shrinkage stress is an index indicating the magnitude of the force acting in the direction of shrinkage of the laminate film when the temperature is changed. By reducing the thermal shrinkage stress, when the laminate film is heated at the time of use, deformation can be suppressed, and processing defects and lamination can be suppressed. Changes in membrane properties. More preferably, the thermal shrinkage stress at a temperature of 100° C. is 0.5 MPa or less, and in this case, the thermal deformation of the laminated film can be suppressed even in a processing step or in actual use.

In the laminated film of the present invention, it is also preferable that the absolute value of TMA represented by the following formula (1) in the orientation axis direction of the laminated film is 0.5% or less at a temperature of 100°C. In the following formula (1), L and ΔL represent the length in the orientation axis direction of the laminated film at a temperature of 25°C, and the displacement of the length of the laminated film when the temperature is changed from the temperature of 25°C, respectively. TMA is an index indicating the ratio of shrinkage or elongation of the laminated film when the temperature is changed. By reducing the absolute value of TMA, deformation when the laminated film is heated during use can be suppressed, processing defects and changes in film performance can be suppressed. The absolute value of TMA at a temperature of 100° C. is preferably 0.5% or less, and in this case, thermal deformation of the film can be suppressed even in a processing step or in actual use.

·TMA=|ΔL/L|×100%...(1)

In the present invention, the laminated film can be formed into a film roll wound along the orientation axis of the laminated film. As described above, in processing steps such as punching, cutting, coating, and lamination, especially in the step of continuous processing using a roll-shaped film, the improvement of the Young's modulus in the longitudinal direction of the laminated film stabilizes the processing steps This is effective, and by obtaining a film roll wound along the orientation axis of the laminated film, when a product is obtained using the laminated film of the present invention, a high-quality product can be easily obtained.

In order to obtain such a film roll, it is a preferable aspect that the angle formed by the orientation axis direction of the laminated film and the flow direction in the film production process is 10° or less. When the angle formed between the orientation axis direction of the laminated film and the flow direction in the production process of the film is 10° or less, the obtained laminated film is continuously wound into a roll shape, thereby performing punching, cutting, coating and layering. In a processing step such as pressing, particularly in a step of continuously processing using a roll-shaped film, the orientation axis direction and the flow direction of the processing step become the same, so that the stabilization of the processing step becomes easy.

Actually, the winding direction of the film roll can be regarded as the flow direction in the film manufacturing process, and in an actual product, the angle formed by the orientation axis direction of the laminated film and the winding direction of the film roll is 10° or less.

In the laminated film of this invention, it is preferable that the A layer which consists of crystalline polyester A is an outermost layer. In this case, since the crystalline polyester A becomes the outermost layer, it can be handled in the same manner as a crystalline polyester film such as a polyethylene terephthalate film and a polyethylene naphthalate film. , to manufacture biaxially stretched films. When the thermoplastic resin B, which is not a crystalline polyester, but is made of, for example, an amorphous resin, becomes the outermost layer, and a biaxially stretched film is obtained in the same manner as the crystalline polyester film, there may be cases in which the Problems such as poor film formation and deterioration of surface properties due to sticking on manufacturing equipment such as rolls and clips.

As the crystalline polyester A usable in the present invention, polyesters obtained by polymerization of monomers mainly composed of aromatic dicarboxylic acids or aliphatic dicarboxylic acids and diols can be preferably used.

Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, etc. As aliphatic dicarboxylic acid, adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and these ester derivatives etc. are mentioned, for example. These acid components may be used alone or in combination of two or more.

In particular, as the carboxylic acid component constituting the crystalline polyester A used in the laminated film of the present invention, terephthalic acid and 2,6 can be preferably used from the viewpoints of exhibiting a high refractive index and increasing Young's modulus. - Naphthalenedicarboxylic acid. Since terephthalic acid and 2,6-naphthalenedicarboxylic acid contain an aromatic ring having high symmetry, it is easy to achieve both a high refractive index and a high Young's modulus by orienting and crystallizing them. In particular, when the carboxylic acid component constituting the crystalline polyester A contains 2,6-naphthalenedicarboxylic acid, by increasing the volume ratio of the aromatic ring, a high Young's modulus can be achieved, and since it can be used industrially. It can be obtained in general, so it can be a low-cost product.

More preferably, 80 mol% or more of 2,6-naphthalenedicarboxylic acid is contained in the carboxylic acid component constituting the crystalline polyester. By containing 80 mol% or more of naphthalenedicarboxylic acid, by performing stretching and heat treatment at the time of production of a laminated film, orientation crystallization can be easily performed, and high Young's modulus can be easily obtained.

Moreover, as a glycol component, ethylene glycol, 1, 2- propanediol, 1, 3- propanediol, neopentyl glycol, 1, 3- butanediol, 1, 4- butanediol, 1,3-butanediol, ,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, Triethylene glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, isosorbate, spiroglycol, and the like. Among them, from the viewpoint of easy polymerization, ethylene glycol as a main component is a preferred embodiment.

The main component here means 80 mol% or more of the diol component. More preferably, it is 90 mol% or more. These diol components may be used alone or in combination of two or more. A part of hydroxy acids such as hydroxybenzoic acid may be copolymerized.

As the thermoplastic resin B that can be used in the present invention, a chain polyolefin such as polyethylene, polypropylene, and poly(4-methyl-1-pentene) can be used; as a norbornene-based ring-opening metathesis polymer, Addition polymers, alicyclic polyolefins of addition copolymers with other olefins; polyamides such as nylon 6, nylon 11, nylon 12, nylon 66, aramid, polymethyl methacrylate, polychlorine Ethylene, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate Ester; polytrimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate, polylactic acid, polysuccinic acid Polyester such as butyl ester; polyether sulfone, polyether ether ketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, tetrafluoroethylene resin, trifluoroethylene resin , chlorotrifluoroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, and polyvinylidene fluoride, etc.

Among these, in addition to the viewpoints of strength, heat resistance, transparency, and versatility, from the viewpoints of adhesiveness and lamination properties with the crystalline polyester A used in the A layer, polyester can be preferably used. ester. They can be used either as copolymers or as mixtures.

In the laminated film of the present invention, in the case where the thermoplastic resin B is a polyester, it is possible to preferably use a monomer containing an aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, and a diol component as main constituent components. Polyester obtained by polymerization. Here, as the aromatic dicarboxylic acid component, the aliphatic dicarboxylic acid component, and the diol component, the components listed in the crystalline polyester A can be suitably used.

In the laminated film of the present invention, the thermoplastic resin B is preferably an aromatic polyester mainly composed of an aromatic dicarboxylic acid component and a diol component. In particular, as a more preferable aspect, in 100 mol % of the dicarboxylic acid component, 40 to 75 mol % is 2,6-naphthalenedicarboxylic acid, and 25 to 60 mol % is selected from isophthalic acid and 1,8-naphthalenedicarboxylic acid. , 2,3-naphthalenedicarboxylic acid, in 100 mol % of the diol component, 80 to 100 mol % are ethylene glycol.

Isophthalic acid, 1,8-naphthalenedicarboxylic acid, and 2,3-naphthalenedicarboxylic acid have the effect of bending the molecular chain depending on the molecular skeleton. As a result, the crystallinity of the thermoplastic resin B is reduced, and the stretching orientation is possible. As a result, when the stretched film is produced, the increase in the refractive index accompanying the orientation crystallization of the B layer can be suppressed, and the refractive index difference with the A layer formed of the crystalline polyester A can be easily generated (in the case of polarized light reflection performance). , is the refractive index difference with the orientation axis of the A layer). As a result, it becomes possible to exhibit higher optical properties, especially in the case of exhibiting polarized light reflection properties.

In order to obtain a laminated film having an interference reflection function, it is also a preferable aspect that the thermoplastic resin B is an amorphous resin. Compared with crystalline resins, amorphous resins are less likely to be oriented during the production of biaxially stretched films. Therefore, the increase in refractive index accompanying the oriented crystallization of the B layer formed of the thermoplastic resin B can be suppressed, and it can be easily generated. It is different from the refractive index of the A layer which consists of crystalline polyester A. In particular, when a heat treatment process is provided at the time of producing a stretched film, this effect becomes remarkable.

Among the orientations generated in the stretching process, the orientation generated in the B layer can be completely relaxed in the heat treatment process, and the difference in refractive index with the A layer made of crystalline polyester can be maximized.

Here, the term "amorphous resin" refers to a resin in which the resin is heated from 25°C to a temperature of 300°C at a temperature increase rate of 20°C/min in accordance with JIS K7122 (1999) (1st RUN), and maintained in this state for 5 After 10 minutes, quenching was then performed so that the temperature became 25°C or lower, and the temperature was raised again from room temperature to 300°C at a temperature increase rate of 20°C/min, and the differential scanning calorimetry chart of 2ndRUN was obtained. Among them, a resin whose crystal fusion heat ΔHm calculated from the peak area of the melting peak is 5 J/g or less is more preferably a resin which does not show a peak corresponding to crystal fusion.

In addition, in order to obtain a laminated film having an interference reflection function, as the thermoplastic resin B, it is also preferable to use a crystalline resin having a melting point lower than that of the crystalline polyester A by 20° C. or more. In this case, in the heat treatment step, by performing heat treatment at a temperature between the melting point of the thermoplastic resin B and the melting point of the crystalline polyester A, it can be completely relaxed in the heat treatment step, and it can be combined with the crystalline polymer. The difference in refractive index of the A layer formed by the ester A is maximized. The difference between the melting points of the crystalline polyester A and the thermoplastic resin B is preferably 40°C or more. In this case, since the selection range of the temperature in the heat treatment step is widened, the promotion of the relaxation of the orientation of the thermoplastic resin B and the control of the orientation of the crystalline polyester can be facilitated.

As a preferable combination of the crystalline polyester A and the thermoplastic resin B, the absolute value of the difference between the SP values of both is preferably 1.0 or less. When the absolute value of the difference in SP value is 1.0 or less, the interlayer peeling between the A layer and the B layer becomes less likely to occur. More preferably, the crystalline polyester A and the thermoplastic resin B are formed of a combination providing the same basic skeleton.

The basic skeleton here means a repeating unit constituting the resin. For example, polyethylene naphthalate containing only 2,6-naphthalenedicarboxylic acid as the carboxylic acid component, or 2,6-naphthalenedicarboxylic acid as the main component of the carboxylic acid component (80% or more of the carboxylic acid component is used) 2,6-Naphthalic acid) polyethylene naphthalate copolymer as the crystalline polyester A, as the thermoplastic resin B, it is preferable to use an amorphous polyethylene naphthalate copolymer It is a crystalline polyethylene naphthalate copolymer whose melting point is lower than that of crystalline polyester A.

In addition, in order to obtain a laminated film having an interference reflection function, the glass transition temperature of the thermoplastic resin B is preferably lower than the glass transition temperature of the crystalline polyester A by 10° C. or more. In this case, when an optimum stretching temperature is used to stretch the crystalline polyester in the stretching step, the orientation in the thermoplastic resin B does not progress, and therefore, the crystalline polyester can be The refractive index difference of the formed A layer is large. More preferably, the glass transition temperature of the thermoplastic resin B is lower than the glass transition temperature of the crystalline polyester A by 20° C. or more.

In a suitable production method for obtaining the laminated film of the present invention, which will be described later, orientation crystallization of the thermoplastic resin B may easily progress, and the desired interference reflection function may not be obtained. The temperature is lower than the glass transition temperature of the crystalline polyester A by 20° C. or more, so that orientation crystallization can be suppressed.

In addition, various additives such as antioxidants, heat-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic additives, etc. Particles, fillers, antistatic agents, and nucleating agents, etc.

In the laminated film of the present invention, preferably, the reflectance when the incident angle of the polarized light component parallel to the incident plane containing the orientation axis direction of the laminated film is 10° is denoted as R1, and the reflectance with respect to the laminated film containing the laminated film is preferably When the incident angle of the polarized light component perpendicular to the incident plane in the orientation axis direction is 10°, the reflectance at a wavelength of 550 nm satisfies the following equations (2) and (3) when the reflectance is denoted as R2. By satisfying the following formulas (2) and (3), it is possible to impart polarized light reflection characteristics such as reflection of a certain polarized light and transmission of the other polarized light.

In order to obtain a film satisfying the following formula (2), the difference in refractive index between the A layer and the B layer in the orientation axis direction of the laminated film can be adjusted to 0.02 or less, more preferably 0.01 or less, and still more preferably 0.005 or less. adjusted in combination. In addition, in order to obtain a film satisfying the following formula (3), the difference in refractive index between the A layer and the B layer in the direction perpendicular to the orientation axis direction of the laminated film can be made 0.08 or more, more preferably 0.1 or more, still more preferably It adjusts for selection of the combination of 0.15 or more resin, and film-forming conditions. Examples of the most suitable combinations thereof are as described above.

·R2(550)≤40%...(2)

·R1(550)≥70%...(3).

In the laminated film of the present invention, in the first heating curve in DSC, the laminated film preferably has a melting peak Tm, and the melting peak peak top temperature Tm - 110°C or higher and Tm - 60°C or lower are in the range. Has an exothermic peak. In order to exhibit the above-mentioned polarization characteristics, the control of the refractive index of each layer becomes important, which makes the control of orientation and crystallinity important. In this control, the difference in refractive index between the orientation direction and the direction perpendicular to the orientation direction is increased by highly orienting the A layer formed of the crystalline polyester A in one direction. On the other hand, it is necessary to control the refractive index of the B layer and the A layer so that one of the refractive indices (mainly in the direction of low refractive index) and the other (mainly in the direction of high refractive index) are matched, and the refractive index difference of the B layer is controlled. orientation and crystallinity become important.

As a result of intensive research by the present inventors, as an index for controlling the B layer, the laminated film has a melting peak Tm in the first temperature rise curve in DSC, and the melting peak peak top temperature Tm-110°C is found. High optical properties can be obtained by having an exothermic peak in the range from Tm to 60°C or lower.

This exothermic peak is a peak showing the exothermic heat generated by the crystallization of the B layer, and thus serves as an index of the orientation and crystallinity of the B layer. In the absence of this exothermic peak, during the film-forming process of the B layer, the orientational crystallization progresses, or the crystallinity is very low, etc., so that the relationship with the refractive index of the A layer is not in the expected range, and the optical characteristic decline.

In addition, even if there is an exothermic peak, when it is outside the range of Tm-110°C or more and Tm-60°C or less, the B layer is over-oriented, showing anisotropy, or the crystallinity is extremely reduced; The relationship of the refractive index is not within the desired range, and the optical properties are degraded. Therefore, in the laminated film of this invention, it has an exothermic peak in the range of Tm-110 degreeC or more and Tm-60 degreeC or less, and this is essential for obtaining high optical characteristics.

As a method of forming a laminated film having an exothermic peak at Tm-110°C or higher and Tm-60°C or lower, the following methods are exemplified. , the temperature in the stretching step, the magnification and the stretching speed are in the preferred ranges. These methods are also preferably carried out in combination of a plurality of types.

In the laminated film of the present invention, it is preferable that the exothermic heat in the exothermic peak is 0.1 J/g or more and 10 J/g or less. The heat release amount is more preferably 0.5 J/g or more and 5 J/g or less, and further preferably 1.5 J/g or more and 4 J/g or less. When the amount of heat release is outside the range of 0.1 J/g or more and 10 J/g or less, the B layer is over-oriented and anisotropy is exhibited, or the crystallinity is extremely reduced; etc., the relationship with the refractive index of the A layer is not expected. range, the optical properties decrease. In the laminated film of the present invention, high optical properties can be obtained by setting the heat release amount in the exothermic peak to 0.1 J/g or more and 10 J/g or less.

The laminated film of the present invention preferably has a melting peak temperature Tm of 255°C or higher. The melting peak temperature is more preferably 258°C or higher. In order to satisfy the range of the above-mentioned melting peak temperature, an aspect of selecting a resin in a more preferable range among the above-mentioned resins can be mentioned, whereby the optical properties can be improved and a film with high heat resistance can be formed.

Next, the preferable manufacturing method of the laminated|multilayer film of this invention is demonstrated below.

In addition, the laminated structure of the laminated film which can be used in the present invention can be easily realized by a method similar to that described in paragraphs [0053] to [0063] of JP-A No. 2007-307893.

First, the crystalline polyester A and the thermoplastic resin B are prepared in the form of pellets or the like. The pellets are supplied to separate extruders after drying in hot air or vacuum as necessary. In the extruder, the resin that has been heated and melted is uniformized by a gear pump or the like, and the foreign matter, modified resin, etc. are removed by a filter or the like. These resins are fed into a multilayer lamination apparatus.

As the multilayer lamination apparatus, a multi-manifold die, a feed block, a static mixer, or the like can be used, and in order to obtain the structure of the present invention efficiently, a feed block having 11 or more fine slits is preferably used. By using such a feed head, the apparatus does not become very large, so there are few foreign matters due to thermal degradation, and even when the number of stacks is very large, high-precision stacking can be performed. In addition, the lamination accuracy in the width direction is also remarkably improved as compared with the prior art. In addition, with this device, the thickness of each layer can be adjusted by the shape (length, width) of the slit, so that any layer thickness can be realized.

Then, the laminated sheet discharged from the die is extruded onto a cooling body such as a casting drum, and is cooled and solidified, whereby a cast film can be obtained. In this case, it is preferable to use electrodes such as wire-shaped, belt-shaped, needle-shaped, or blade-shaped, and the discharged sheet is brought into close contact with the cooling body by electrostatic force, and it is quenched and solidified. In addition, as a method of making the discharged sheet adhere to the cooling body, a method of blowing air from a slit-shaped, spot-shaped, and planar-shaped device, and a method of using a nip roll are also preferable.

The cast film obtained as described above is preferably biaxially stretched. The biaxial stretching here means stretching the film in the longitudinal direction and the width direction.

In addition, as a preferred biaxial stretching method for obtaining the laminated film of the present invention, it is necessary to stretch the film widthwise by 2 to 5 times after stretching at a magnification ratio of 2 to 5 times in the longitudinal direction of the film. , and further stretched by 1.3 to 4 times in the longitudinal direction of the film. The details are as follows.

The obtained cast film is first stretched in the longitudinal direction. The stretching in the longitudinal direction can usually be carried out by utilizing the difference in the peripheral speed of the rolls. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. The stretching ratio varies depending on the type of resin, but is preferably 2 to 5 times. The purpose of the first stretching in the longitudinal direction is to provide the minimum required orientation in order to improve the uniform stretchability during the subsequent stretching in the width direction of the film. Therefore, when the stretching ratio is set to a ratio of more than 5 times, a film with a sufficient stretching ratio may not be obtained during stretching in the width direction of the film described later and re-stretching in the longitudinal direction performed after the step. . In addition, when the stretching ratio is less than 2 times, the minimum orientation required for stretching cannot be imparted, and thickness unevenness may occur in the longitudinal direction of the film, resulting in deterioration of quality. In addition, the stretching temperature is preferably a temperature ranging from the glass transition temperature of the crystalline polyester A constituting the laminated film to the glass transition temperature+30°C.

The uniaxially stretched film obtained as described above may be subjected to surface treatments such as corona treatment, flame treatment, and plasma treatment, and then in-line coating to impart easy slipperiness and adhesion to the uniaxially stretched film, if necessary. and anti-static properties.

Next, the uniaxially stretched film is stretched in the width direction. For the stretching in the width direction, generally, a tenter is used, and the film is conveyed while sandwiching both ends of the film with clips, and stretching is performed in the width direction. The stretching ratio varies depending on the type of resin, but is usually preferably 2 to 5 times. The purpose of this stretching in the width direction is to provide the minimum orientation required for imparting high stretchability in the subsequent stretching in the longitudinal direction of the film. Therefore, when the draw ratio is set to a ratio of more than 5 times, a film with a sufficient draw ratio may not be obtained at the time of redrawing in the film longitudinal direction followed by this step. Moreover, when a draw ratio is less than 2 times, thickness unevenness may generate|occur|produce in the film width direction at the time of extending|stretching, and may result in the deterioration of quality. In addition, the stretching temperature is preferably between the glass transition temperature of the crystalline polyester A constituting the laminated film to the glass transition temperature+30°C, or the glass transition temperature to the crystallization temperature of the crystalline polyester.

Next, the obtained biaxially stretched film is stretched again in the longitudinal direction. The stretching in the longitudinal direction can generally be performed by utilizing the difference in the peripheral speed of the rolls. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. The stretching ratio varies depending on the type of resin, but is preferably 1.3 to 4 times. The purpose of the above-mentioned second stretching in the longitudinal direction is to orient the film as strongly as possible in the longitudinal direction of the film. By stretching again in the longitudinal direction as described above, the resin is strongly oriented, and as a result, the lamination can be made. The Young's modulus in the orientation axis direction of the film is 6 GPa or more, and the linear expansion coefficient in the direction in which the Young's modulus is the largest (the orientation axis direction of the laminated film) is 10 ppm/°C or less. In particular, the higher the stretching ratio in the longitudinal direction, the more the Young's modulus can be increased, or the more the linear expansion coefficient can be suppressed, the Young's modulus can be made 10GPa or more, and the linear expansion coefficient can be made 40°C or more and 50°C or less. The absolute value also becomes easy to be 5 ppm/°C or less. In addition, the stretching temperature is preferably from the glass transition temperature of the crystalline polyester A constituting the laminated film to the glass transition temperature+80°C.

In order to impart planarity and dimensional stability to the film biaxially stretched as described above, it is preferable to perform heat treatment in a tenter at a temperature equal to or higher than the stretching temperature and equal to or lower than the melting point. By performing the heat treatment, not only the effect of promoting orientation crystallization and increasing Young's modulus is obtained, but also dimensional stability is improved along with the promotion of orientation crystallization. The absolute value of the linear expansion coefficient at a temperature of 40°C to 50°C in any direction perpendicular to the orientation axis direction of the laminated film is possible to be 5 ppm/°C or less. In addition, it is also possible to make the thermal shrinkage stress at a temperature of 100°C in the orientation axis direction 1 MPa or less and the absolute value of TMA at a temperature of 100°C in the orientation axis direction to be 0.5% or less. After the heat treatment is performed as described above, it is cooled uniformly and gradually, and then cooled to normal temperature and wound. In addition, if necessary, relaxation treatment or the like may be performed when slowly cooling is performed after the heat treatment.

The laminated film obtained by the above-described production method can be formed into a laminated film which not only has a high Young's modulus but also has polarized light reflection characteristics satisfying the above-mentioned formulas (2) and (3). This is because at the time of the second stretching in the longitudinal direction of the film, the orientation of the layer A formed of the crystalline polyester A can be made stronger in the longitudinal direction of the film. As a result, the refractive index in the longitudinal direction of the film is the same as the sum of A difference occurs between the refractive indices in the film width direction perpendicular to the film length direction. Furthermore, by selecting an amorphous resin as the thermoplastic resin B, or selecting a combination of the crystalline polyester A and the thermoplastic resin B having differences in glass transition temperature and melting point that can alleviate orientation in the stretching step and the heat treatment step, it is possible to By suppressing the orientation of the thermoplastic resin B, polarized light reflection characteristics can be imparted.

(Measuring method of characteristics and evaluation method of effect)

The measurement method of the characteristic in this invention and the evaluation method of an effect are as follows.

(1) Number of layers:

The layer structure of the laminated film was obtained by observing, using a transmission electron microscope (TEM), a sample whose cross section was cut out with a microtome. That is, using a transmission electron microscope H-7100FA (manufactured by Hitachi, Ltd.), a cross-sectional photograph of the film was taken under the conditions of an accelerating voltage of 75 kV, and the layer structure and the thickness of each layer were measured. In some cases, in order to improve the contrast, a dyeing technique using RuO ₄ , OsO ₄ or the like is used. In addition, according to the thickness of the thinnest layer (thin film layer) among all the layers captured in one image, when the thickness of the thin film layer is less than 50 nm, it is observed at a magnification of 100,000 times, and the thin film layer is observed at a magnification of 100,000 times. When the thickness is 50 nm or more and less than 500 nm, observation is performed at a magnification of 40,000 times, and when the thickness of the thin film layer is 500 nm or more, observation is performed at a magnification of 10,000 times.

(2) Calculation method of layer thickness and number of layers:

The TEM photograph image obtained in the above-mentioned item (1) was captured at an image size of 720 dpi using a scanner (CanoScan D1230U manufactured by Canon Co., Ltd.). Save the image as a bitmap file (BMP) or compressed image file (JPEG) on a personal computer, and then use the image processing software Image-Pro Plus ver.4 (Seller: プラネトロン Co., Ltd.) ) to open the file for image analysis. In the image analysis processing, the relationship between the position in the thickness direction and the average luminance of the area sandwiched between two lines in the width direction is read as numerical data in the vertical thickness profile mode.

Using table calculation software (Excel 2000), for the position (nm) and luminance data, data collection was performed using sampling step 2 (thinning 2), and then numerical processing of a 5-point moving average was performed. Further, differentiate the obtained data of periodic brightness change, use VBA (Visual Basic for Applications) program to read the maximum value and minimum value of the differential curve, and compare the adjacent regions with maximum brightness to The interval between the extremely small regions was used as the layer thickness of one layer, and the layer thickness was calculated. This operation is performed for each photograph, and the layer thickness and number of layers of all layers are calculated.

(3) Young's modulus:

The laminated film was cut into a strip shape of 150 mm in length and 10 mm in width, and used as a sample. The tensile test was performed using a tensile tester (Tensilon UCT-100, manufactured by Orienttec), with the initial tensile grip distance set to 50 mm, and the tensile speed set to 300 mm/min. The measurement was performed in an atmosphere of room temperature 23°C and relative humidity of 65%, and the Young's modulus was determined from the obtained load-strain curve. The measurement was performed five times for each sample, and the average value thereof was used for evaluation.

(4) The orientation axis direction of the laminated film:

The Young's modulus of the laminated film was measured by changing the direction every 10° in the film surface, and the direction in which the Young's modulus became the largest was defined as the orientation axis direction of the laminated film.

(5) Linear expansion coefficient:

The laminated film was cut into a strip shape of length 25 mm×width 4 mm along the direction of the orientation axis, and used as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the initial tensile chucks was 15 mm, and the tensile tension was kept constant at 29.4 mN. In this state, the temperature in the testing machine was changed from 25 °C to 5 °C/min The temperature was raised to 150°C, and TMA measurement was performed on the orientation axis direction of the laminated film. From the obtained TMA-temperature curve, the coefficient of linear expansion at a temperature of 40°C to 50°C was obtained.

(6) Thermal shrinkage stress:

The laminated film was cut into a strip shape of length 25 mm×width 4 mm along the direction of the orientation axis, and used as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the tensile chucks was kept constant at 15 mm, and in this state, the temperature in the testing machine was raised from 25°C to 150°C at 5°C/min. The thermal shrinkage stress was measured with respect to the orientation axis direction of the laminated film. From the obtained stress-temperature curve, the thermal shrinkage stress was obtained.

(7) TMA:

The laminated film was cut into a strip shape of length 25 mm×width 4 mm along the direction of the orientation axis, and used as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the initial tensile chucks was 15 mm, and the tensile tension was kept constant at 29.4 mN. In this state, the temperature in the testing machine was changed from 25 °C to 5 °C/min. The temperature was raised to 150°C, and TMA measurement was performed on the orientation axis direction of the laminated film. From the obtained TMA-temperature curve, TMA was calculated|required.

(8) Determination of reflectivity and transmittance of incident light with polarized components:

From the center of the orientation axis direction on the line segment where the length in the orientation axis direction becomes the largest, a sample is cut out at 5 cm×5 cm. Using the basic configuration using the integrating sphere attached to the Hitachi, Ltd. spectrophotometer (U-4100 Spectrophotomater), the measurement was performed on the basis of an alumina sub-whiteboard attached to the device. The sample was placed behind the integrating sphere with the direction of the orientation axis of the laminated film as the vertical direction. In addition, an attached polarizer made by Grantel Corporation was installed, and linearly polarized light whose polarized light component was polarized at 0 and 90° was incident, and the reflectance at a wavelength of 250 to 1500 nm was measured.

The measurement conditions are as follows. The slit was set to 2 nm (visible)/automatic control (infrared), the gain was set to 2, the measurement was performed at a scanning speed of 600 nm/min, and the reflectance at an azimuth angle of 0 to 180 degrees was obtained. When measuring the reflection of the sample, in order to eliminate the interference due to the reflection from the back surface, it was blackened with Majikink (registered trademark).

In addition, about the sample cut out in the same manner, the transmittance was measured in the same manner without blackening, and from the obtained transmittance data, the extinction ratio at a wavelength of 550 nm was obtained by the following formula.

·Extinction ratio = T2/T1

(Here, T1 represents the transmittance of the polarized light component parallel to the incident plane including the orientation axis direction of the laminated film when the incident angle is 0°, and T2 represents the incident angle when the incident angle is 0°. The transmittance of the polarized light component perpendicular to the plane of incidence in the direction of the orientation axis.)

(9) The peak intensity ratio I max/I min of the polarized Raman spectrum:

The polarization Raman spectrum was measured using a laser Raman spectrometer T-64000 manufactured by Jovin Yvon Corporation. The laminated film was cut out with a microtome so that the direction of the maximum reflectance determined in the above item (4) was Imax and the direction perpendicular to it was Imin, and the cut surfaces in each direction became the measurement surface section. The polarization Raman spectrum was measured with the case where the polarization axis of the laser light from the cross section of the sample coincides with the transmission axis of the film as the parallel condition, and the case where it coincides with the thickness direction of the laminated film as the perpendicular condition. For the measurement, three points were measured at the center of each layer by changing the position, and the average value was taken as the measurement value. The detailed measurement conditions are as follows.

Measurement mode: Micro Raman

·Objective lens: ×100

Beam diameter: 1μm

Cross slit: 100μm

Light source: Ar+laser/514.5nm

·Laser power: 15mW

Diffraction grating: Spectrograph 600gr/mm

·Dispersion: Single 21 angstroms/mm

·Slit: 100μm

• Detector: CCD/Jobin Yvon 1024×256.

Regarding the peak intensity ratio I max/I min of the polarized Raman spectrum at a wavelength of 1390 cm ^-1 and a wavelength of 1615 cm ^-1 , the 1390 cm ^-1 of the CNC stretching band derived from the naphthalene ring obtained by the measurement of the polarized Raman spectrum The peak intensity of the benzene ring and the peak intensity of 1615 cm ^-1 derived from the C=C stretching band of the benzene ring are determined by the peak intensity of the sample with the cross section in the Imax direction and the sample with the measurement plane in the Imin direction. Calculate the ratio.

(10) Melting enthalpy and glass transition temperature:

A sample was taken from the measured laminated film, and the DSC curve of the measured sample was measured according to JIS-K-7122 (1987) using differential calorimetry (DSC). In the test, the temperature was raised from 25°C to 290°C at 20°C/min, and the melting enthalpy and glass transition temperature at that time were measured. The apparatus etc. used are as follows.

・Device: "Robot DSC-RDC220" manufactured by Seiko Electronics Co., Ltd.

・Data analysis "ディスクセッションSSC/5200"

· Sample mass: 5 mg.

(11) Processability:

The roll-shaped film was introduced into a punching machine so that the length was 500 mm, and punching was performed using a rectangular die having a widthwise length of 95% with respect to the film width. In addition, the punching interval in the longitudinal direction was set to 40 mm. The following A, B, and C evaluations were performed. Take A and B as qualified.

A: The film can be continuously conveyed and processed without breaking.

B: Although the film was partially broken, continuous transport in the longitudinal direction was possible, and continuous processing was possible.

C: The film was completely broken, and continuous processing in the longitudinal direction was not performed.

(12) Installation test:

From the position of the central part in the film width direction, the laminated film as a sample was cut out with a size of 1450 mm in the longitudinal direction x 820 mm in the width direction. Next, on the 32-type liquid crystal TV LHD32K15JP backlight source manufactured by Hizen Co., Ltd., a 50% diffuser plate, a microlens sheet, a polarizing light reflector, and a polarizing plate were arranged in this order, and the temperature was 50°C and 85°C. , the flatness of the polarized light reflector after the 12-hour heat resistance test was visually evaluated.

The evaluation of flatness was determined by the following A, B, and C. Take A as qualified.

A: At 50°C and 85°C, there is no problem in appearance

B: There is a problem with the appearance at a temperature of 50°C.

(13) The content rate of naphthalenedicarboxylic acid:

The layer A of the laminated film composed of the crystalline polyester was dissolved in deuterated hexafluoroisopropanol (HFIP) or a mixed solvent of HFIP and deuterated chloroform, and composition analysis was performed using 1H-NMR and 13C-NMR.

Example

(Example 1)

As the crystalline polyester A, 2,6-polyethylene naphthalate (PEN) having a melting point of 266°C and a glass transition temperature of 122°C was used. In addition, as the thermoplastic resin B, 25 mol % of spiroglycol 2,6-naphthalenedicarboxylate, 25 mol % of terephthalic acid, and ethyl acetate, which are amorphous resins having no melting point and a glass transition temperature of 103° C., were used. Copolymerized PEN obtained by copolymerizing 50 mol% of diol (copolymerized PEN1).

The prepared crystalline polyester A and thermoplastic resin B were put into two single-screw extruders, respectively, and melt-kneaded at a temperature of 290°C. Next, after passing the crystalline polyester A and the thermoplastic resin B through five FSS-type leaf disk filters, respectively, they were measured with a gear pump, and were separated by a laminating device with 11 slits. By merging, a laminate in which 11 layers were alternately stacked in the thickness direction was obtained. The method of forming the laminate is carried out in accordance with the method described in paragraphs [0053] to [0056] of JP-A No. 2007-307893.

Here, the length and interval of the slits are all constant. The obtained laminate had a laminate structure in which 6 layers of crystalline polyester A and 5 layers of thermoplastic resin B were alternately laminated in the thickness direction. In addition, the value obtained by dividing the film width direction length of the die lip by the film width direction length at the inflow port of the die, which is the widening ratio inside the die, was 2.5. The width of the obtained cast film was 600 mm.

The obtained cast film was heated with a roll set set to a temperature of 120°C, then stretched to 3.0 times in the longitudinal direction of the film with a roll set to a temperature of 135°C, and then cooled temporarily. The uniaxially stretched film obtained as described above was introduced into a tenter, preheated with hot air at a temperature of 115°C, and then stretched 3.0 times in the width direction of the film at a temperature of 135°C to obtain a film roll. Biaxially stretched film. The width of the biaxially stretched film obtained here was 1500 mm.

In addition, the biaxially stretched film was heated with a set of rolls set at a temperature of 120°C, and then stretched 3.0 times in the longitudinal direction of the film with rolls set at a temperature of 160°C, and both ends of the film were trimmed, The target laminated film was obtained in the form of a film roll with a film width of 1000 mm and a length of 200 m.

The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the MD direction. In addition, interference reflection characteristics due to the difference in refractive index between the crystalline polyester A and the thermoplastic resin B are shown. The laminated film of the present invention can be favorably used when it is processed into a product or when it is actually used.

(Example 2)

A laminated film was obtained in the same manner as in Example 1, except that an apparatus having 101 slits was used as the lamination apparatus used.

The obtained laminated film showed physical properties as shown in Table 1, and similarly to Example 1, showed a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the film longitudinal direction. In addition, the interference reflection characteristics due to the difference in refractive index between the crystalline polyester A and the thermoplastic resin B were shown, and compared with Example 1, the high polarized light reflection characteristics were shown. This laminated film can be continuously produced with high accuracy and stably when it is processed into a product, and can be used without any problems in actual use.

(Example 3)

A laminated film was obtained in the same manner as in Example 1, except that an apparatus having 201 slits was used as the lamination apparatus used.

The obtained laminated film exhibited physical properties as shown in Table 1, and, as in Example 1, exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the MD direction. In addition, the interference reflection characteristics due to the difference in refractive index between the crystalline polyester A and the thermoplastic resin B were shown, and compared with Example 2, high polarized light reflection characteristics were exhibited, which were at a level usable as a polarized light reflection member. This laminated film can be continuously produced with high accuracy and stably when it is processed into a product, and can be used without any problems in actual use.

(Example 4)

A laminated film was obtained in the same manner as in Example 1, except that an apparatus having 801 slits was used as the lamination apparatus used. The obtained laminated film exhibited physical properties as shown in Table 1, and, as in Example 1, exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the MD direction. In addition, it exhibited interference reflection characteristics due to the difference in refractive index between the crystalline polyester A and the thermoplastic resin B. Compared with Example 3, it exhibited high polarized light reflection characteristics, and had very good performance as a polarized light reflection member. . This laminated film can be continuously produced with high accuracy and stably when it is processed into a product, and can be used without any problems in actual use.

(Example 5)

A laminated film was obtained in the same manner as in Example 4, except that the magnification when the biaxially stretched film was stretched again in the film longitudinal direction was 2.5 times. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50°C). In addition, as in Example 4, high polarized light reflection characteristics were exhibited, and very good performance was exhibited as a polarized light reflection member. This laminated film can be continuously produced with high accuracy and stably when it is processed into a product, and can be used without any problems in actual use.

(Example 6)

A laminated film was obtained in the same manner as in Example 4, except that the magnification when the biaxially stretched film was stretched again in the film longitudinal direction was 2.2 times. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50°C). This laminated film can be continuously produced even when it is processed into a product under specific conditions, and can also be used without problems when actually used.

(Example 7)

A laminated film was obtained in the same manner as in Example 4, except that the magnification when the biaxially stretched film was stretched again in the film longitudinal direction was 2.0 times. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50°C). This laminated film can be continuously produced even when it is processed into a product under specific conditions, and can also be used without problems when actually used.

(Example 8)

After the biaxially stretched film was stretched again in the longitudinal direction, the laminated film was obtained in the same manner as in Example 4, except that the biaxially stretched film was transported into an oven heated to a temperature of 180° C. to perform heat treatment. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50°C). In addition, as in Example 4, high polarized light reflection characteristics were exhibited, and very good performance was exhibited as a polarized light reflection member. In addition, compared with Example 4, the obtained film can suppress the thermal shrinkage stress at 100° C. in the film longitudinal direction and the absolute value of TMA to be low. When processed into a product, it can be continuously produced with high accuracy and stably, and in actual use, it can be used without problems even under conditions more severe than that of Example 4.

(Example 9)

After the biaxially stretched film was stretched again in the longitudinal direction, the laminate film was obtained in the same manner as in Example 4, except that the biaxially stretched film was transferred into an oven heated to a temperature of 220° C. to perform heat treatment. The obtained laminated film exhibited the physical properties shown in Table 2, and exhibited a high Young's modulus and a low coefficient of linear expansion (40 to 50°C). In addition, as in Example 4, high polarized light reflection characteristics were exhibited, and very good performance was exhibited as a polarized light reflection member. In addition, compared with Example 4, in the obtained laminated film, the thermal shrinkage stress at 100° C. in the film longitudinal direction and the absolute value of TMA can be suppressed to be low, and this laminated film is in a specific When processed into a product under the conditions, it can be continuously produced with high accuracy and stably, and in actual use, it can be used without problems even under severer conditions than in Example 4.

(Example 10)

As the crystalline polyester, copolymerized PEN (PEN) obtained by copolymerizing 50 mol% of 2,6-naphthalenedicarboxylic acid, 5 mol% of spiroglycol, and 45 mol% of ethylene glycol with a melting point of 240°C and a glass transition temperature of 118°C was used ( Except for copolymerizing PEN2), it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film showed physical properties as shown in Table 2, and showed a high Young's modulus. This laminated film can be continuously produced even when it is processed into a product under specific conditions, and can also be used without problems when actually used.

(Example 11)

Except having used copolymerized PEN2 as thermoplastic resin B, it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film showed physical properties as shown in Table 2, and similarly to Example 4, showed a high Young's modulus. On the other hand, since the difference in the glass transition temperature of the crystalline polyester and the thermoplastic resin B is small, the reflection performance is comparable to that of Example 1. This laminated film can be continuously produced with high accuracy and stably when it is processed into a product, and can be used without any problems in actual use.

(Example 12)

As the crystalline polyester, polyethylene terephthalate (PET) having a melting point of 256° C. and a glass transition temperature of 81° C. was used, and as the thermoplastic resin B, an amorphous resin having a glass transition temperature of A laminated film was obtained in the same manner as in Example 4, except that PET (co-PET) was copolymerized with cyclohexanedimethanol at 78°C. The obtained laminated film showed physical properties as shown in Table 2, and compared with Comparative Examples 1 to 5, it showed a high Young's modulus. This laminated film can be continuously produced even when it is processed into a product under specific conditions, and can be used without problems when actually used. On the other hand, since the crystalline polyester is PET, the reflection performance becomes lower than that of Example 4.

(Example 13)

As the thermoplastic resin B, a glass transition temperature of 96° C. was obtained by copolymerizing 70 mol % of 2,6-naphthalenedicarboxylic acid and 30 mol % of isophthalic acid as a dicarboxylic acid component and using ethylene glycol as a diol component. Except that the copolymerized PEN (copolymerized PEN3) was obtained, a laminated film was obtained in the same manner as in Example 4. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used.

(Example 14)

After the biaxial stretching, a laminated film was obtained in the same manner as in Example 13, except that the rate of stretching the film in the longitudinal direction was 400%/sec. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Example 15)

As the thermoplastic resin B, one having a glass transition temperature of 90° C., 50 mol % of 2,6-naphthalenedicarboxylic acid and 50 mol % of isophthalic acid as the dicarboxylic acid component and ethylene glycol as the diol component was used and copolymerized Except for the copolymerization of PEN (copolymerization PEN4), it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Example 16)

As the thermoplastic resin, a copolymer having a glass transition temperature of 98° C., 75 mol % of 2,6-naphthalenedicarboxylic acid and 25 mol % of isophthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component was used. Except for PEN (copolymerized PEN5), it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Example 17)

As the thermoplastic resin B, one having a glass transition temperature of 103° C., 80 mol % of 2,6-naphthalenedicarboxylic acid and 20 mol % of isophthalic acid as the dicarboxylic acid component and ethylene glycol as the diol component was used and copolymerized A laminated film was obtained in the same manner as in Example 4, except that PEN was copolymerized (PEN6 copolymerized). The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Example 18)

As the thermoplastic resin B, a glass transition temperature of 103° C., 70 mol % of 2,6-naphthalenedicarboxylic acid and 30 mol % of 1,8-naphthalenedicarboxylic acid were used as the dicarboxylic acid component, and ethylene glycol was used as the diol component and copolymerized Except for the obtained copolymerized PEN (copolymerized PEN7), it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Example 19)

As thermoplastic resin B, copolymerized PEN having a glass transition temperature of 103° C., 70 mol % of 2,6-naphthalenedicarboxylic acid, 30 mol % of 2,3-naphthalenedicarboxylic acid, and ethylene glycol as a diol component was used. (Copolymerization PEN8), except having carried out similarly to Example 4, the laminated|multilayer film was obtained. The obtained laminated film showed physical properties as shown in Table 3, and showed a high Young's modulus. This laminated film can be continuously produced when it is processed into a product, and can be used without problems when actually used. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarization reflection performance was excellent.

(Comparative Example 1)

A film was obtained in the same manner as in Example 4, except that a single-layer film of PEN was used as the cast film. The obtained film showed physical properties as shown in Table 2, and as in Example 4, showed a high Young's modulus. On the other hand, since it does not have a laminated structure, it does not show specific reflection performance, and compared with the film of Example 1, since a film becomes brittle, handleability falls. With this film, film breakage occurred when it was processed into a product, and the continuous productivity was poor.

(Comparative Example 2)

A laminated film was obtained in the same manner as in Example 1, except that an apparatus having three slits was used as the lamination apparatus used. The obtained laminated film showed physical properties as shown in Table 2, and similarly to Example 1, showed a high Young's modulus in the film longitudinal direction. On the other hand, since the number of layers was as small as 3, the reflection performance peculiar to the laminated structure was not exhibited, and the film became brittle compared with the film of Example 1, so the handleability was slightly lowered. In this laminated film, film breakage occurred when it was processed into a product, and the continuous productivity was poor.

(Comparative Example 3)

The cast film obtained in the same manner as in Example 4 was heated with a set of rolls set at a temperature of 120°C, and then stretched to 4.5 times in the longitudinal direction of the film with a roll set at a temperature of 135°C, Then cool down for a while.

The uniaxially stretched film obtained as described above was introduced into a tenter, preheated with hot air at a temperature of 135°C, stretched 4.5 times in the width direction of the film at a temperature of 150°C, and then conveyed to It heat-processed in the oven heated to 220 degreeC. By trimming both ends of the obtained biaxially stretched film, the target laminated film was obtained as a film roll with a film width of 1500 mm and a length of 200 m.

The obtained laminated film showed physical properties as shown in Table 2, and compared with Example 4, the Young's modulus decreased. In this laminated film, film breakage occurred when it was processed into a product, and the continuous productivity was poor.

(Comparative Example 4)

The cast film obtained in the same manner as in Example 4 was introduced into a tenter, preheated with hot air at a temperature of 135°C, stretched 5.0 times in the width direction of the film at a temperature of 150°C, and trimmed. Both ends, thereby obtaining a 200-m target laminated film in a roll shape with a film width of 2,000 mm.

The obtained laminated film showed physical properties as shown in Table 2, and compared with Example 4, the Young's modulus decreased. Moreover, since it is a film which has an orientation axis|shaft in the width direction of this film roll, the intensity|strength of the winding-axis direction of a film roll is very weak. In this laminated film, film breakage occurred when it was processed into a product, and the continuous productivity was poor.

(Comparative Example 5)

The cast film obtained in the same manner as in Example 4 was heated with a set of rolls set at a temperature of 120° C., and then stretched to 4.0 times in the lengthwise direction of the film by means of a roll set at a temperature of 135° C. , and trimming was performed to obtain a target film roll formed of a laminated film with a film width of 500 mm and a length of 200 m.

The obtained laminated film showed physical properties as shown in Table 2, and compared with Example 4, the Young's modulus decreased. In addition, with the orientation of the thermoplastic resin B generated at the time of stretching, the reflective performance was also greatly reduced compared with the Examples. In this laminated film, film breakage occurred when it was processed into a product, and the continuous productivity was poor.

[Table 1]

Table 1

[Table 2]

[table 3]

Claims (12)

1. A laminated film, wherein a layer A made of a crystalline polyester and a layer B made of a thermoplastic resin different from the crystalline polyester are alternately laminated in a total of 11 or more layers, so The Young's modulus in the orientation axis direction of the laminated film is 6 GPa or more, and the ratio of the Young's modulus in the orientation axis direction to the direction perpendicular to the orientation axis direction in the same plane is 10.2/3.1 or more, And layer A and layer B meet the following conditions, A layer: formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, 80 to 100 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, and the 80-100 mol% of the diol component 100mol% is ethylene glycol; Layer B: It is formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, and 40 to 75 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, and 25 to 25 mol % 60 mol % is at least one component selected from isophthalic acid, 1,8-naphthalenedicarboxylic acid and 2,3-naphthalenedicarboxylic acid, and 80-100 mol % of the diol component 100 mol % is ethylene glycol. 2 . The laminated film according to claim 1 , wherein, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1390 cm ⁻¹ , the peak intensity I max in the direction with the highest reflectance and a direction perpendicular to the same The ratio Imax/Imin of the peak intensity Imin is 5 or more. 3 . The laminated film according to claim 1 , wherein 90 mol % or more of naphthalenedicarboxylic acid is contained in the carboxylic acid component constituting the crystalline polyester. 4 . 4 . The laminated film according to claim 1 , wherein linear expansion at a temperature of 40° C. or higher and 50° C. or lower in any one of an orientation axis direction and a direction perpendicular to the orientation axis direction. 5 . The absolute value of the coefficient is 10 ppm/°C or less. 5 . The laminate film according to claim 1 , wherein the reflectance when the incident angle of the polarized light component parallel to the incident plane including the orientation axis direction is 10° is denoted as R1 , and the reflectance is denoted as R1 . When the reflectance at the incident angle of the polarized light component perpendicular to the incident plane including the orientation axis direction is 10°, when the reflectance is denoted as R2, the reflectance at a wavelength of 550 nm satisfies the following formulas (2) and (3) ), ·R2(550)≤40% (2) · R1(550) ≥ 70% (3). 6. The laminated film according to claim 1 or 2, wherein the laminated film has a melting peak in the first heating curve obtained by differential scanning calorimetry (DSC), and when the temperature of the melting peak is denoted as Tm , has an exothermic peak in the range of Tm-110°C or higher and Tm-60°C or lower. 7 . The laminate film according to claim 1 , wherein the thermal shrinkage stress at a temperature of 100° C. in the orientation axis direction is 1 MPa or less. 8 . 8 . The laminate film according to claim 1 , wherein the absolute value of TMA at a temperature of 100° C. in the orientation axis direction is 0.5% or less. 9 . 9 . The laminate film according to claim 1 , wherein the melting peak derived from the thermoplastic resin B measured by differential scanning calorimetry DSC is 5 J/g or less. 10 . A film roll obtained by winding the laminated film according to any one of claims 1 or 2 along the orientation axis of the laminated film. 11 . The width of the laminated film is 1000 mm or more, The film roll of Claim 10 characterized by the above-mentioned. 12. A method for producing a laminated film, wherein a layer A made of crystalline polyester and a layer B made of a thermoplastic resin different from the crystalline polyester are alternately laminated to a total of 11 or more layers. The stretched film is stretched in the longitudinal direction of the film at a magnification of 2 to 5 times, then stretched in the width direction of the film at a magnification of 2 to 5 times, and further stretched in the longitudinal direction of the film at a magnification of 1.3 to 4 times stretch, And layer A and layer B meet the following conditions, A layer: formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, 80 to 100 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, and the 80-100 mol% of the diol component 100mol% is ethylene glycol; Layer B: It is formed of an aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, and 40 to 75 mol % of 100 mol % of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, and 25 to 25 mol % 60 mol % is at least one component selected from isophthalic acid, 1,8-naphthalenedicarboxylic acid and 2,3-naphthalenedicarboxylic acid, and 80-100 mol % of the diol component 100 mol % is ethylene glycol.