CN107405908A - Stacked film and its manufacture method - Google Patents

Abstract

A kind of various functions with as stacked film of present invention offer and stacked film that can be to be processed in high yield and in high precision with high mechanical properties, in various manufacturing procedures.The stacked film of the present invention is characterised by：It is the A layers formed by crystalline polyester and the alternately laminated stacked film for adding up to more than 11 layers and being formed of the B layers formed by the thermoplastic resin different from foregoing crystalline polyester, and the Young's modulus of the orientation direction of principal axis (the maximum direction of Young's modulus) of foregoing stacked film is more than 6GPa.

Description

Laminated film and manufacturing method thereof

technical field

The present invention relates to laminated films and methods for their manufacture.

Background technique

For thermoplastic resin films, especially biaxially stretched polyester films, due to their excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency and chemical resistance, they are widely used in magnetic recording materials, packaging materials, etc. It is widely used as a substrate film in various applications.

On the other hand, for polyester films, laminated films in which different resins are alternately laminated are used. For such a laminated film, it can become a film with special functions that cannot be obtained by a single-layer film. For example, it can be mentioned: a tear-resistant film with improved tear strength (see Patent Document 1.), An infrared reflective film that reflects infrared rays (see Patent Document 2.), a polarized light reflective film having polarized light reflection properties (see 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 laminated thickness. If the mechanical strength and dimensional stability of the laminated film are reduced, for example, when it is combined with other various films and members, and processed to form a functional film such as punching, cutting, coating, and lamination, it will be damaged due to 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 during processing, and reduction in optical properties and quality of the obtained film; or, when actually mounted on a product, etc., dimensional changes occur accompanying adverse conditions.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 3960194

Patent Document 2: Japanese Patent No. 4310312

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

Contents of the invention

The problem to be solved by the invention

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

means to solve the problem

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 A layer made of crystalline polyester and B layer made of a thermoplastic resin different from the aforementioned crystalline polyester are alternately laminated. In a laminated film having a total of 11 or more layers, the Young's modulus in the direction of the orientation axis (the direction in which the Young's modulus is the largest) of the laminated film is 6 GPa or more.

According to a preferred form of the laminated film of the present invention, for the aforementioned laminated film, in the 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 the maximum reflectance is perpendicular to it. The ratio I max/I min of the peak intensity I min in the direction is 5 or more.

According to a preferred embodiment of the laminated film of the present invention, naphthalene dicarboxylic acid is contained in an amount of 90 mol % or more in the carboxylic acid component constituting the aforementioned crystalline polyester.

According to a preferred aspect of the laminated film of the present invention, the absolute value of the coefficient of linear expansion at a temperature of 40° C. to 50° C. Below 10ppm/°C.

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 at a wavelength of 550 nm satisfies the following formulas (2) and (3) when the incident angle of the polarized light component perpendicular to the plane of incidence in the orientation axis direction is 10° and the reflectance is denoted as R2.

·R2(550)≤40％···(2)

·R1(550)≥70%···(3)

According to a preferred aspect of the laminated film of the present invention, the laminated film has a melting peak in the first temperature rise curve obtained by differential calorimetry (hereinafter referred to as DSC) of the laminated film, and the peak top temperature of the melting peak is When 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 preferred aspect of the laminated film of the present invention, the Young's modulus ratio of the orientation axis direction of the laminated film to a direction perpendicular to the orientation axis direction in the same plane is 2 or more.

According to a preferred aspect of the laminated film of the present invention, the thermal shrinkage stress at a temperature of 100° C. in the orientation axis direction of the laminated film is 1 MPa or less.

According to a preferred aspect of the laminated film of the present invention, the absolute value of TMA at a temperature of 100° C. in the orientation axis direction of the laminated film is 0.5% or less.

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

According to a preferred embodiment of the laminated film of the present invention, the layer A and the layer B satisfy the following conditions.

・A layer: formed of aromatic polyester mainly composed of dicarboxylic acid components and diol components, 80 to 100 mol% of 100 mol% of the aforementioned dicarboxylic acid components are 2,6-naphthalene dicarboxylic acid, and the aforementioned diol components 80-100 mol% of 100 mol% of components is ethylene glycol.

・B layer: formed of aromatic polyester mainly composed of dicarboxylic acid component and diol component, 40-75mol% of the above-mentioned dicarboxylic acid component 100mol% is 2,6-naphthalene dicarboxylic acid, 25-60mol % is at least one component selected from isophthalic acid, 1,8-naphthalene dicarboxylic acid, and 2,3-naphthalene dicarboxylic acid, and 80 to 100 mol% of 100 mol% of the diol component 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 preferred aspect of the film roll of the present invention, the width of the laminated film is 1000 mm or more.

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

The effect of the invention

According to the present invention, it is possible to obtain a laminated film having high mechanical strength and dimensional stability, which can be processed or used as various functional films such as punching, cutting, coating, and lamination. Appropriate use can exhibit the effect that it can be used without causing problems during actual installation.

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

detailed description

Next, the laminated film of the present invention and its manufacturing method will be described in detail.

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

Here, the so-called crystalline polyester A specifically refers to the following polyester: According to JIS K7122 (1999), differential scanning calorimetry (hereinafter, sometimes referred to as DSC.) Heat the resin from 25°C to 300°C (1st RUN), keep it in this state for 5 minutes, then perform rapid cooling to a temperature below 25°C, and then increase the temperature from 25°C at a rate of 20°C/min. The temperature is raised to 300°C, and the obtained 2ndRUN differential scanning calorimetry chart has a crystal fusion heat ΔHm of 15 J/g or more obtained from the peak area of the melting peak. More preferably, the crystal fusion heat is 20 J/g or more, still more preferably 25 J/g or more.

In addition, the thermoplastic resin B is a thermoplastic resin that exhibits different optical or thermal properties from 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 directions perpendicular to the plane of the laminated film and a direction perpendicular to the plane, or a thermoplastic resin that exhibits a refractive index different from that of a crystalline polymer in DSC. Ester A is a thermoplastic polyester with different melting points and glass transition temperatures.

In addition, the term "alternate lamination" here means that the A layer and the B layer are laminated in a regular arrangement in the thickness direction. For example, a regular arrangement represented by A(BA)n (n is a natural number) is stacked. By alternately laminating resins having different optical properties as described above, interference reflection capable of reflecting light having a wavelength designed based on 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 is possible to highly control the orientation state of each layer when manufacturing a biaxially stretched film, and it becomes possible to control optical properties, mechanical properties, and thermal shrinkage properties.

As a preferred laminated form of the laminated film, there is also a layer A formed of a crystalline polyester A, a layer B formed of a thermoplastic resin B different from the crystalline polyester A, and a layer B formed of a thermoplastic resin B different from the crystalline polyester A The case of layer C formed of thermoplastic resin C different from ester A and thermoplastic resin B. In this case, layers C such as CA(BA)n, CA(BA)nC, and A(BA)nCA(BA)m may be stacked on the outermost layer or intermediate layer.

In addition, when the number of laminated layers is less than 11 layers, different thermoplastic resins are laminated to affect various physical properties such as film forming properties and mechanical properties. Therefore, for example, it may become difficult to manufacture a biaxially stretched film. However, when it is manufactured into a product, problems may occur.

On the other hand, in the case of a laminated film in which a total of 11 or more layers are alternately laminated like the laminated film of the present invention, each thermoplastic resin can be uniformly arranged compared to a laminated film having fewer than 11 layers. Therefore, film-forming properties and mechanical properties can be stabilized. In addition, as the number of layers increases, there is a tendency to suppress the growth of orientation in each layer. 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 laminated layers is preferably 100 or more, more preferably 200 or more. When the film is stacked in 100 or more layers, it is possible to reflect light in a wide area with high reflectance, and in the case of stacking 200 or more layers, it is possible to reflect almost all visible light with a wavelength of 400 to 700 nm, for example. In addition, there is no upper limit to the number of stacked layers, 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 device. Therefore, in practice, within 10,000 layers 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 direction of the orientation axis of the laminated film here refers to the direction in which the Young's modulus of the film is measured by changing the direction every 10° in the film surface, and the Young's modulus becomes the maximum. Young's modulus is an index indicating the force required for the initial deformation of the film. By making the Young's modulus high, it can be used even in processing steps such as punching, cutting, coating, and lamination, or when used as a functional film. Deformation can also be suppressed when a force is applied to the laminated film, and it is easy to suppress processing defects and performance changes during use that are accompanied by deformation of the film.

The Young's modulus in the orientation axis direction of the laminated film is preferably 8 GPa or more, more preferably 10 GPa or more. As the Young's modulus increases, the laminated film becomes less likely to be deformed. For example, the control range of processing conditions such as punching, cutting, coating, and lamination becomes wider. Therefore, not only can processing defects be suppressed, but also for improving 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 also realized by the production method of the film.

In addition, in the case of a single layer or a few layers, if the Young's modulus in the direction of the orientation axis of the laminated film 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 drop.

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

In addition, in the laminated film of the present invention, it is also a preferred embodiment that the ratio of the Young's modulus in the direction of the orientation axis of the laminated film to the direction perpendicular thereto in the same plane is 2 or more. When it is desired to increase the ratio of Young's modulus simply by selecting the resin and the method of producing the film, for a laminated film having uniform Young's modulus in the in-plane direction of the laminated film, Young's modulus There is a limit to the quantity. This is because the Young's modulus depends on the strength of the orientation of the resin constituting the laminated film, and thus how strong the orientation is in the direction in which the Young's modulus is to be increased affects the magnitude of the Young's modulus.

On the other hand, in processing processes such as punching, cutting, coating, and lamination, especially in the process of continuous processing using a roll-shaped film, the stabilization of the processing process by increasing the Young's modulus in the longitudinal direction of the laminated film It is vaild. Therefore, by setting the ratio of the Young's modulus in the direction of the orientation axis of the laminated film to the direction perpendicular to it in the same plane as 2 or more, the Young's modulus on the side of the orientation axis can be further increased, and the direction in which the Young's modulus is the largest The Young's modulus (in the orientation axis direction of the laminated film) becomes 6 GPa or more easily. More preferably, the ratio of the Young's modulus in the orientation axis direction of the laminated film to the direction perpendicular to the same plane is 3 or more. In this case, the Young's modulus in 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 with the largest reflectance to the peak intensity I min in the direction perpendicular to it I max/I min is preferably 5 or more. The direction in which the reflectance is the largest here means that the incident surface of the polarized light component is 0° with respect to the laminated film, the incident angle is 0°, and the direction is changed every 10° in the laminated film surface. For reflectivity, reflectivity shows the direction of maximum value.

In addition, the peak observed in the polarized Raman spectrum with a wavelength of 1390 cm ^-1 belongs to the CNC stretching band of the naphthalene ring, which can pass the peak intensity I max in the direction with the largest reflectivity and the peak intensity I min in the direction perpendicular to it The ratio Imax/Imin is used to determine the orientation state of the naphthalene ring. I max/I min at a wavelength of 1390 cm ^-1 is preferably 5.5 or more, 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 high orientation can increase the Young's modulus. Regarding the upper limit of I max/I min at a wavelength of 1390 cm ⁻¹ , it is possible to prevent the layer A formed of crystalline polyester A containing naphthalene dicarboxylic acid from being formed of thermoplastic resin B different from crystalline polyester A The upper limit is preferably 20, more preferably 10, and particularly preferably 7 or less from the viewpoint of deteriorating interlayer adhesion due to increased differences in the orientation state and crystallinity of the B layer. I max/I min at a wavelength of 1390 cm ⁻¹ can be adjusted by selecting the combination of resins for the A layer and 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 of the maximum reflectance to the peak intensity I min in the direction perpendicular to it It is preferable that I max/I min is 4 or more.

The peak observed in the polarized Raman spectrum with a wavelength of 1615cm ^-1 belongs to the C=C stretching band of the benzene ring, which can pass through the difference between the peak intensity I max in the direction of the maximum reflectivity and the peak intensity I min in the direction perpendicular to it The ratio I max/I min was used to determine the orientation state of the benzene ring. I max/I min at a wavelength of 1615 cm ⁻¹ is preferably 4.5 or more, more preferably 5 or more. When the 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 high orientation increases the Young's modulus.

Regarding the upper limit of I max/I min at a wavelength of 1615 cm ⁻¹ , it is possible to prevent the layer A formed of a crystalline polyester A containing naphthalene dicarboxylic acid from being formed of a thermoplastic resin B different from the crystalline polyester A. The upper limit is preferably 20 or less, more preferably 10 or less, particularly preferably 6 or less, from the viewpoint of deteriorating interlayer adhesiveness due to increased differences in the orientation state and crystallinity of the B layer. I max/I min at a wavelength of 1615 cm ⁻¹ can be adjusted by selecting the combination of resins for the A layer and B layer and the film forming conditions. Examples of the optimal combinations 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 of the maximum reflectance to the peak intensity I min in the direction perpendicular to it I max/I min is preferably 5 or more.

In the laminated film of the present invention, the absolute value of the coefficient of linear expansion at a temperature of 40°C to 50°C needs to be 10 ppm/°C in either direction of the orientation axis direction of the laminated film or a direction perpendicular to the orientation axis direction of the laminated film. the following. The so-called 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 can be used in processing steps such as punching, cutting, coating, and lamination, or as a film. When the functional film is used, even when the temperature of the laminated film changes, the deformation of the film can be suppressed, and it is easy to suppress the processing failure accompanying the deformation of the film and the performance change during use.

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

In addition, when the absolute value of the linear expansion coefficient at a temperature of 40°C to 50°C in the direction of the orientation axis of the laminated film is 10 ppm/°C or less in the case of a single layer or a few layers, due to the orientation of the resin, strength, there is a tendency for the film to become brittle, and the handleability may also be reduced. On the other hand, as in the present invention, a laminated film formed by alternately laminating a total of 11 or more layers of layers A made of crystalline polyester A and layers B made of thermoplastic resin B different from the aforementioned crystalline polyester A In some cases, even if the absolute value of the coefficient of linear expansion at a temperature of 40°C to 50°C is 10ppm/°C or less, due to the interfacial tension at the lamination interface and the cushioning effect of the B layer formed of thermoplastic resin B, the operation will not be damaged. The linear expansion coefficient is significantly reduced, and even when force is applied to the laminated film during punching, cutting, coating, lamination and other processing steps, or when used as a functional film, the effect of suppressing deformation can be obtained.

In addition, in the laminated film of the present invention, it is also a preferred embodiment that the thermal shrinkage stress at a temperature of 100° C. in the direction of the orientation axis of the laminated film is 1 MPa or less. Thermal shrinkage stress is an index indicating the magnitude of the force acting in the direction of shrinkage of the laminated film when the temperature is changed. By reducing the thermal shrinkage stress, when the laminated film is heated during use, deformation can be suppressed, and processing defects and lamination can be suppressed. The performance of the membrane changes. More preferably, the thermal shrinkage stress at a temperature of 100° C. is 0.5 MPa or less. In this case, thermal deformation of the laminated film can be suppressed even during processing or 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 direction of the orientation axis 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 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 of the laminated film during use can be suppressed, and processing defects and film performance changes can be suppressed. The absolute value of TMA at a temperature of 100 is preferably 0.5% or less. In this case, thermal deformation of the film can be suppressed even during processing or 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 mentioned above, in the processing steps such as punching, cutting, coating and lamination, especially in the process of continuous processing using roll-shaped film, increasing the Young's modulus in the longitudinal direction of the laminated film contributes to the stabilization of the processing process Effectively, by obtaining a film roll wound along the orientation axis of the laminated film, a high-quality product can be easily obtained when the laminated film of the present invention is used to obtain a product.

In order to obtain such a film roll, it is a preferred aspect that the angle formed by the direction of the orientation axis of the laminated film and the flow direction in the film production process is 10° or less. When the angle between the direction of the orientation axis of the laminated film and the flow direction in the film production process is 10° or less, the obtained laminated film is continuously wound into a roll, so that it can be used in punching, cutting, coating and layering. In processing steps such as pressing, especially in a step of continuously processing using a roll-shaped film, the direction of the orientation axis becomes the same as the flow direction in the processing step, and thus 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 actual products, 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 the present invention, the layer A formed of the crystalline polyester A is preferably the outermost layer. In this case, since the crystalline polyester A becomes the outermost layer, it can be handled in the same way as a crystalline polyester film such as a polyethylene terephthalate film or a polyethylene naphthalate film. , to manufacture biaxially stretched films. When the thermoplastic resin B formed of, for example, a non-crystalline resin other than a crystalline polyester is used as the outermost layer, when a biaxially stretched film is obtained in the same manner as a crystalline polyester film, the Problems such as poor film formation and deterioration of surface properties due to sticking to 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, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6- Naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenyl sulfone dicarboxylic acid, etc. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid, and their ester derivatives. 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 - Naphthalene dicarboxylic acid. Since terephthalic acid and 2,6-naphthalene dicarboxylic acid contain aromatic rings with high symmetry, it becomes 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-naphthalene dicarboxylic acid, by increasing the volume ratio of the aromatic ring, a high Young's modulus can be achieved, and since it can be used in industry It is commonly available in the world, and thus can be a low-cost product.

More preferably, 80 mol% or more of 2,6-naphthalene dicarboxylic acid is contained in the carboxylic acid component constituting the crystalline polyester. When 80 mol% or more of naphthalene dicarboxylic acid is contained, orientation crystallization can be easily performed by stretching and heat treatment during the production of the laminated film, and high Young's modulus becomes easy.

In addition, examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1 ,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, spirodiol, and the like. Among them, from the viewpoint of easiness of polymerization, ethylene glycol is a preferred embodiment as a main component.

Here, the main component 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 and the like may also be copolymerized.

As the thermoplastic resin B usable in the present invention, chain polyolefins such as polyethylene, polypropylene, and poly(4-methyl-1-pentene) can be used; ring-opening metathesis polymers such as norbornenes, Addition polymers, alicyclic polyolefins of addition copolymers with other olefins; nylon 6, nylon 11, nylon 12, nylon 66 and other polyamides, aramids, polymethylmethacrylate, polychloride Ethylene, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate Esters; Polytrimethylene terephthalate, Polyethylene terephthalate, Polybutylene terephthalate, Polyethylene-2,6-naphthalate, Polylactic acid, Polysuccinic acid Polyester such as butyl ester; polyethersulfone, 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 general versatility, from the viewpoints of adhesion to the crystalline polyester A used in the A layer and laminarity, polyester can be preferably used. ester. They can be used either as copolymers or as mixtures.

In the laminated film of the present invention, when the thermoplastic resin B is a polyester, it is preferable to use a compound composed of a monomer mainly composed of an aromatic dicarboxylic acid component and/or an aliphatic dicarboxylic acid component and a diol component. polymerized polyester. 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 form, in 100 mol% of the dicarboxylic acid component, 40 to 75 mol% is 2,6-naphthalene dicarboxylic acid, and 25 to 60 mol% is selected from the group consisting of isophthalic acid and 1,8-naphthalene dicarboxylic acid. , the component in 2,3-naphthalene dicarboxylic acid, in 100 mol% of the diol component, 80-100 mol% is ethylene glycol.

Isophthalic acid, 1,8-naphthalene dicarboxylic acid, and 2,3-naphthalene dicarboxylic acid have the effect of bending the molecular chain according to their molecular skeleton, and as a result, the crystallinity of the thermoplastic resin B is lowered, and the stretching time is reduced. orientation becomes possible. As a result, when producing a stretched film, 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 layer A). 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 preferable that the thermoplastic resin B is an amorphous resin. Compared with crystalline resins, amorphous resins are less likely to be oriented in the production of biaxially stretched films, so the increase in the refractive index accompanying the oriented crystallization of the layer B formed of thermoplastic resin B can be suppressed, and can be easily generated. The refractive index is different from that of the layer A formed of crystalline polyester A. This effect becomes remarkable especially when a heat treatment process is provided at the time of manufacturing a stretched film.

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

Here, the term "amorphous resin" refers to a resin that is heated from 25°C to 300°C at a temperature increase rate of 20°C/min (1st RUN) according to JIS K7122 (1999), and kept in this state for 5 Minutes later, quenching is performed next to lower the temperature below 25°C, and the temperature is raised again from room temperature to 300°C at a rate of 20°C/min. Among them, the resin whose heat of crystal fusion ΔHm obtained from the peak area of the melting peak is 5 J/g or less is more preferably a resin that does not show a peak corresponding to crystal melting.

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 is possible to make it possible to combine with the crystalline polyester A. The difference in refractive index of the A layer formed by ester A is maximized. Preferably, the difference between the melting points of the crystalline polyester A and the thermoplastic resin B is 40° C. or more. In this case, the selection range of the temperature in the heat treatment step becomes wider, so that the promotion of the orientation relaxation of the thermoplastic resin B and the control of the orientation of the crystalline polyester become easier.

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, delamination 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 term "basic skeleton" here refers to a repeating unit constituting the resin. For example, use polyethylene naphthalate whose carboxylic acid component consists only of 2,6-naphthalene dicarboxylic acid or use 2,6-naphthalene dicarboxylic acid as the main component of the carboxylic acid component (the carboxylic acid component contains 80% or more In the case of a polyethylene naphthalate copolymer of 2,6-naphthalene dicarboxylic acid) as the crystalline polyester A, as the thermoplastic resin B, it is preferable to use an amorphous polyethylene naphthalate copolymer A crystalline polyethylene naphthalate copolymer having a melting point 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, in the stretching process, when the most suitable stretching temperature is used for stretching the crystalline polyester, the orientation in the thermoplastic resin B does not progress, so that the The formed layer A has a large difference in refractive index. 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 described later, orientation crystallization of the thermoplastic resin B tends to progress, and the desired interference reflection function cannot be obtained. However, by making the glass transition of the thermoplastic resin B The temperature is 20° C. or more lower than the glass transition temperature of the crystalline polyester A, 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 Particles, fillers, antistatic agents, and nucleating agents, etc.

In the laminated film of the present invention, it is preferable that 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 When the incident angle of the polarized light component perpendicular to the plane of incidence in the orientation axis direction is 10°, the reflectance is denoted as R2, and the reflectance at a wavelength of 550 nm satisfies the following formula (2) and formula (3). By satisfying the following formulas (2) and (3), it is possible to impart polarized light reflection characteristics that reflect one polarized light and transmit another 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 0.02 or less, more preferably 0.01 or less, and even more preferably 0.005 or less resin. combined to adjust. In addition, in order to obtain a film satisfying the following formula (3), the refractive index difference between the A layer and the B layer in the direction perpendicular to the orientation axis direction of the laminated film can be 0.08 or more, more preferably 0.1 or more, and more preferably 0.1 or more. It is adjusted for the selection of the combination of resins of 0.15 or more 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, it is preferable that the laminated film has a melting peak Tm in the first heating curve in DSC, and the melting peak peak 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 layer A formed of the crystalline polyester A is highly oriented in one direction, thereby increasing the difference in refractive index between the orientation direction and the direction perpendicular thereto. On the other hand, it is necessary to make one of the refractive indices of the B layer and the A layer (mainly the direction with a low refractive index) coincide, and increase the difference in refractive index with the other (mainly the direction with a high refractive index), so as to control the thickness of the B layer. Orientation and crystallinity become important.

The inventors of the present invention conducted in-depth studies and found that, as an index for controlling the B layer, the laminated film has a melting peak Tm in the first heating curve in DSC, and the melting peak peak temperature Tm-110°C There is an exothermic peak in the range of the above Tm - 60° C. or lower, whereby high optical characteristics can be obtained.

This exothermic peak is a peak showing the exothermic heat caused by the crystallization of the B layer, and thus serves as an indicator of the orientation and crystallinity of the B layer. In the absence of this exothermic peak, layer B undergoes oriented crystallization during the film forming process, or the crystallinity is very low, etc., so that the relationship with the refractive index of layer A is out of the desired range. Features drop.

In addition, even if there is an exothermic peak, when it is outside the range of Tm-110°C or higher and Tm-60°C or lower, the B layer is excessively oriented and anisotropic, or the crystallinity is extremely reduced; The relationship of the refractive index is out of the desired range, and the optical characteristics are degraded. Therefore, the laminated film of the present invention has an exothermic peak in the range of Tm - 110°C or higher and Tm - 60°C or lower, which 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 mentioned: the A layer and the B layer are in the aforementioned preferred form; , the temperature, magnification, and stretching speed in the stretching process are set within the preferred ranges. These methods are also preferably performed in combination.

The laminated film of the present invention preferably has an exothermic heat in an exothermic peak of not less than 0.1 J/g and not more than 10 J/g. The amount of heat released is more preferably 0.5 J/g to 5 J/g, still more preferably 1.5 J/g to 4 J/g. When the exothermic value is outside the range of Tm-110°C or higher and Tm-60°C or lower, the B layer is excessively oriented and anisotropic, or the crystallinity is extremely reduced; etc., resulting in an unexpected relationship with the refractive index of the A layer. range, the optical properties degrade. In the laminated film of the present invention, high optical characteristics can be obtained by setting the heat release amount in the heat release 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, a method of selecting a resin in a more preferable range among the above-mentioned resins can be mentioned, whereby the optical characteristics can be improved and a film with high heat resistance can be formed.

Next, a preferred production method of the laminated film of the present invention will be described below.

In addition, the laminated structure of the laminated film usable in the present invention can be easily realized by the same method as described in paragraphs [0053] to [0063] of JP-A-2007-307893.

First, crystalline polyester A and thermoplastic resin B are prepared in the form of pellets or the like. The pellets are supplied to separate extruders after being dried in hot air or under vacuum as necessary. In the extruder, for the heated and melted resin, the extruded amount of the resin is made uniform by a gear pump or the like, and foreign substances, modified resin, etc. are removed by passing through a filter or the like. These resins are fed into a multilayer lamination device.

As a multilayer lamination device, a multi-manifold die, a feed block, a static mixer, etc. can be used. In order to effectively obtain the structure of the present invention, a feed block having 11 or more fine slits is preferably used. By using such a feeding head, since the apparatus does not become very large, there are few foreign substances due to thermal deterioration, and high-precision lamination can be performed even when the number of laminations is very large. In addition, the lamination accuracy in the width direction is also remarkably improved compared to the conventional technology. In addition, with this device, the thickness of each layer can be adjusted according to 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 cooled and solidified to obtain a cast film. At this time, it is preferable to use an electrode such as a wire, a belt, a needle, or a blade to closely adhere the discharged sheet to a cooling body by electrostatic force, and quench and solidify it. In addition, as a method of bringing the discharged sheet into close contact with the cooling body, a method of blowing air from a slit-shaped, dot-shaped, or planar device, and a method of using a nip roll are also preferable.

The cast film obtained in the above manner is preferably biaxially stretched. The term "biaxial stretching" here refers to stretching the film in the longitudinal direction and the width direction.

In addition, as a preferable biaxial stretching method for obtaining the laminated film of the present invention, it is necessary to stretch at a ratio of 2 to 5 times in the longitudinal direction of the film and then stretch at a ratio of 2 to 5 times in the width direction of the film. , and stretched again at 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. Stretching in the longitudinal direction can generally be performed by utilizing the difference in 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 this first stretching in the longitudinal direction is to provide the minimum required orientation in order to improve the uniform stretchability in the subsequent stretching in the width direction of the film. Therefore, when the stretching ratio is set to a ratio greater than 5 times, a film with a sufficient stretching ratio may not be obtained when stretching the film in the width direction described later and re-stretching in the longitudinal direction after this step. . In addition, when the draw ratio is less than 2 times, the minimum orientation required at the time of stretching cannot be imparted, and thickness unevenness may occur in the longitudinal direction of the film, resulting in a decrease in quality. In addition, the stretching temperature is preferably a temperature 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 can be given surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and can be given slipperiness and adhesion by in-line coating. And anti-static and other functions.

Next, the uniaxially stretched film is stretched in the width direction. Stretching in the width direction is usually carried out using a tenter, while both ends of the film are held between clips, and the film is conveyed to stretch 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 greater than 5 times, a film having a sufficient draw ratio may not be obtained at the time of re-stretching in the film longitudinal direction following this step. Moreover, when the draw ratio is less than 2 times, thickness unevenness may arise in the film width direction at the time of stretching, and quality may fall. 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 between the glass transition temperature and the crystallization temperature of the crystalline polyester.

Next, the obtained biaxially stretched film is stretched again in the longitudinal direction. The above-mentioned stretching in the longitudinal direction can generally be implemented by utilizing the difference in 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. By stretching again in the longitudinal direction as described above, the resin is strongly oriented. As a result, the laminated film 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 of the largest Young's modulus (orientation axis direction of the laminated film) is 10 ppm/°C or less. In particular, the higher the stretching ratio along the direction, the more the Young's modulus can be increased, or the linear expansion coefficient can be suppressed, so that the Young's modulus is 10 GPa or more, and the absolute value of the linear expansion coefficient is 40°C to 50°C. The value becomes easy also below 5 ppm/°C. 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 biaxially stretched film as described above, it is preferable to perform heat treatment at a temperature not lower than the stretching temperature and not higher than the melting point in a tenter. By performing heat treatment, not only the orientational crystallization can be accelerated to obtain the effect of increasing the Young's modulus, but also the dimensional stability can be improved along with the acceleration of the orientational crystallization. The absolute value of the linear expansion coefficient at a temperature of 40° C. to 50° C. in either direction perpendicular to the orientation axis direction of the laminated film or the direction perpendicular to the orientation axis direction of the laminated film may 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 direction of the orientation axis 1 MPa or less, and the absolute value of TMA at a temperature of 100° C. in the direction of the orientation axis to be 0.5% or less. After performing the heat treatment as described above, it was uniformly and gradually cooled, and then cooled to room temperature, and then wound. In addition, if necessary, relaxation treatment or the like may be performed during slow cooling after the heat treatment.

The laminated film obtained by the production method as described above can be a laminated film having a high Young's modulus and polarized light reflection characteristics satisfying the aforementioned formulas (2) and (3). This is because, during the second stretching in the longitudinal direction of the film, the orientation of the A layer formed of the crystalline polyester A can be made stronger in the longitudinal direction of the film, and as a result, the refractive index and the 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 a crystalline polyester A and a thermoplastic resin B having a difference in glass transition temperature and melting point that can ease the orientation in the stretching process and the heat treatment process, it is possible to By suppressing the orientation of the thermoplastic resin B, polarized light reflection properties can be imparted.

(Measurement method of characteristics and evaluation method of effect)

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

(1) Number of layers:

The layer structure of the laminated film was obtained by observing a sample whose cross section was cut out using a microtome using a transmission electron microscope (TEM). That is, a cross-sectional photograph of the film was taken at an accelerating voltage of 75 kV using a transmission electron microscope H-7100FA type (manufactured by Hitachi, Ltd.), and the layer structure and thickness of each layer were measured. In some cases, in order to improve the contrast, a dyeing technique using RuO ₄ , OsO ₄ , etc. is used. In addition, based on 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, observe at a magnification of 100,000 times, and the thickness of the thin film layer is less than 50 nm. When the thickness is not less than 50 nm and less than 500 nm, observe at a magnification of 40,000 times, and when the thickness of the thin film layer is not less than 500 nm, observe at a magnification of 10,000 times.

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

Using a scanner (Canon Co., Ltd. CanoScan D1230U), the TEM photograph image obtained in the above item (1) was captured at an image size of 720 dpi. Save the image in the personal computer as a bitmap file (BMP) or a compressed image file (JPEG), and then use the image processing software Image-Pro Plus ver.4 (seller: Planetron Co., Ltd.) ), open the file for image analysis. In the image analysis process, in the vertical thickness profile mode, the relationship between the position in the thickness direction and the average brightness of the region sandwiched between the two lines in the width direction is read as numerical data.

Using spreadsheet software (Excel 2000), the position (nm) and luminance data were collected using sampling step 2 (thinning 2), and numerical processing of 5-point moving average was performed. Furthermore, the obtained data of periodic changes in brightness are differentiated, using a 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 and The intervals between extremely small regions were regarded as the layer thickness of one layer, and the layer thickness was calculated. This operation is performed for each photograph, and the thickness and number of layers of all layers are calculated.

(3) Young's modulus:

The laminated film was cut into a strip shape with a length of 150 mm×a width of 10 mm to prepare a sample. Using a tensile tester (Tensilon UCT-100 manufactured by Orientec), a tensile test was performed by setting the distance between chucks at the initial stage of tension to 50 mm and the tensile speed at 300 mm/min. The measurement was carried out in an atmosphere at room temperature of 23°C and a relative humidity of 65%, and the Young's modulus was obtained 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) Orientation axis direction of 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 with a length of 25 mm×a width of 4 mm along the direction of its orientation axis to prepare a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), set the distance between the initial tensile chucks to 15mm, and keep the tensile tension constant at 29.4mN. The temperature was increased to 150° C., and TMA measurement was performed for 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 determined.

(6) Thermal shrinkage stress:

The laminated film was cut into a strip with a length of 25 mm×a width of 4 mm along the direction of its orientation axis to prepare a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the tensile chucks was kept constant at 15mm. In this state, the temperature inside the testing machine was raised from 25°C to 150°C at 5°C/min. Thermal shrinkage stress was measured for 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 with a length of 25 mm×a width of 4 mm along the direction of its orientation axis to prepare a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), set the distance between the initial tensile chucks to 15mm, and keep the tensile tension constant at 29.4mN. The temperature was increased to 150° C., and TMA measurement was performed for the orientation axis direction of the laminated film. From the obtained TMA-temperature curve, TMA was calculated|required.

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

A sample was cut out at 5 cm×5 cm from the center in the orientation axis direction on the line segment having the maximum length in the orientation axis direction. The basic configuration using the integrating sphere attached to the spectrophotometer (U-4100 Spectrophotomater) manufactured by Hitachi, Ltd. was used for measurement with reference to the secondary white plate of alumina attached to the apparatus. With the direction of the orientation axis of the laminated film as the vertical direction, the sample was placed behind the integrating sphere. In addition, the attached polarizer made by Grantera Co., Ltd. was installed, and linearly polarized light with polarization components 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 2nm (visible)/automatic control (infrared), the gain was set to 2, and the measurement was performed at a scanning speed of 600nm/min to obtain reflectance at an azimuth angle of 0 to 180 degrees. In order to eliminate the interference due to the reflection from the back surface when performing the reflectance measurement of the sample, it was blackened with Magic Inky (registered trademark).

In addition, the transmittance of the sample cut out in the same manner was measured in the same manner without blackening, and the extinction ratio at a wavelength of 550 nm was obtained from the obtained transmittance data using 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 transmittance relative to the incident plane including the orientation axis direction of the laminated film when the incident angle is 0°. The transmittance of the polarized light component perpendicular to the incident plane in the direction of the orientation axis.)

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

The polarized Raman spectrum was measured using a laser Raman spectrometer T-64000 manufactured by Jovin Yvon. For the laminated film, the direction of the maximum reflectance determined in the above item (4) is regarded as Imax, and the direction perpendicular to it is regarded as Imin, and the cut surface in each direction becomes the measurement surface, and is cut out by a microtome. section. In the polarized Raman spectrum, the polarization axis of the laser beam from the cross section of the sample was measured as the parallel condition and the case where it coincided with the thickness direction of the laminated film as the perpendicular condition. About the measurement, the center part of each layer changed the position and measured 3 points, and made the average value into a measured value. Detailed measurement conditions are as follows.

·Determination 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.

For the peak intensity ratio Imax/Imin of the polarized Raman spectrum at the wavelength of 1390cm ^-1 and the wavelength of 1615cm ^-1 , the 1390cm ^-1 of the CNC stretching band derived from the naphthalene ring obtained by the measurement of the polarized Raman spectrum and the peak intensity at 1615 cm ^-1 originating from the C=C stretching band of the benzene ring are determined from the peak intensities of a sample whose measurement surface is a cross-section in the I max direction and a sample whose measurement surface is a cross-section in the I min direction. Figure out the ratio.

(10) Melting enthalpy and glass transition temperature:

The laminated film to be measured was sampled, and the DSC curve of the measurement sample was measured using differential calorimetry (DSC) in accordance with JIS-K-7122 (1987). For 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 and the like used are as follows.

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

・Data Analysis "Disk Session SSC/5200"

• Sample mass: 5 mg.

(11) Processability:

The roll-shaped film was introduced into a punching machine, the length was 500 mm, and punching was performed using a rectangular die having a widthwise length of 95% relative 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 pass.

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

B: Although the film was partially broken, continuous conveyance 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 possible.

(12) Installation test:

The laminated film which is a sample was cut out from the position of the center part of a film width direction, and the dimension of 1450 mm of a longitudinal direction x 820 mm of a width direction. Next, on the 32-type liquid crystal TV LHD32K15JP backlight manufactured by High Sens Japan Co., Ltd., install a 50% diffuser plate, a microlens sheet, a polarized light reflector, and a polarizer in this order, and set the temperature at 50°C and 85°C. , the planarity of the polarized light reflector after the 12-hour heat resistance test was visually evaluated.

Evaluation of planarity was judged by following A, B, and C. Take A as pass.

A: There is no problem with the appearance at the temperature of 50°C and 85°C

B: At a temperature of 50° C., the appearance is problematic.

(13) Naphthalene dicarboxylic acid content:

The layer A formed of crystalline polyester of the laminated film 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 spiro-2,6-naphthalene dicarboxylate, 25 mol% of terephthalic acid, and ethyl Copolymerized PEN obtained by copolymerizing 50 mol % of diol (copolymerized PEN1).

The prepared crystalline polyester A and thermoplastic resin B were charged into two single-screw extruders, respectively, and melt-kneaded at a temperature of 290°C. Next, the crystalline polyester A and the thermoplastic resin B were respectively passed through five FSS-type disc filters (leaf disk filters), and were metered by a gear pump, and were separated by a lamination device with 11 slits. They were merged to obtain a laminate in which 11 layers were alternately laminated in the thickness direction. The method of producing the laminate was carried out in accordance with the method described in paragraphs [0053] to [0056] of JP-A-2007-307893.

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

The obtained cast film was heated with a roll set at a temperature of 120° C., stretched 3.0 times in the film length direction with a roll set at a temperature of 135° C., and then cooled once. The uniaxially stretched film obtained in the above manner is introduced into a tenter, preheated with hot air at a temperature of 115°C, stretched 3.0 times in the width direction of the film at a temperature of 135°C, and obtained in the form of 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 roller group set at a temperature of 120° C., and then stretched to 3.0 times in the longitudinal direction of the film with a roller set at a temperature of 160° C., and both ends of the film were trimmed. The target laminated film was obtained as a film roll having 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 exhibited. The laminated film of the present invention can be suitably used both when processed into a product and when 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 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 film longitudinal direction as in Example 1. In addition, interference reflection characteristics due to the difference in refractive index between crystalline polyester A and thermoplastic resin B were exhibited, and compared with Example 1, high polarized light reflection characteristics were exhibited. When this laminated film is processed into a product, it can be produced continuously with high precision and stably, and can be used without any problem 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 the physical properties shown in Table 1, and had a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the MD direction as in Example 1. 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 2, it showed high polarized light reflection characteristics, which was at a level usable as a polarized light reflection member. When this laminated film is processed into a product, it can be produced continuously with high precision and stably, and can be used without any problem 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 the physical properties shown in Table 1, and had a high Young's modulus and a low coefficient of linear expansion (40 to 50° C.) in the MD direction as in Example 1. In addition, it exhibits interference reflection characteristics due to the difference in refractive index between crystalline polyester A and thermoplastic resin B. Compared with Example 3, it shows high polarized light reflection characteristics, and has very good performance as a polarized light reflection member. . When this laminated film is processed into a product, it can be produced continuously with high precision and stably, and can be used without any problem in actual use.

(Example 5)

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

(Example 6)

A laminated film was obtained in the same manner as in Example 4 except that the ratio when the biaxially stretched film was stretched again in the film longitudinal direction was 2.2 times. The obtained laminated film exhibited the physical properties 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 it can be used without any problem in actual use.

(Example 7)

A laminated film was obtained in the same manner as in Example 4 except that the magnification when stretching the biaxially stretched film in the film longitudinal direction was 2.0 times again. The obtained laminated film exhibited the physical properties 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 it can be used without any problem in actual use.

(Embodiment 8)

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

(Example 9)

After stretching the biaxially stretched film in the longitudinal direction again, it carried out in the oven heated to the temperature of 220 degreeC, and heat-processed, and it carried out similarly to Example 4, and obtained the laminated film. 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, similarly to Example 4, it exhibited high polarized light reflection characteristics, and had very good performance as a polarized light reflection member. In addition, for the obtained laminated film, compared with Example 4, the thermal shrinkage stress at 100° C. in the film longitudinal direction and the absolute value of TMA can be kept low. When processed into products under these conditions, it can be continuously produced with high precision and stability, and in actual use, it can be used without any problem under conditions that are more severe than those in Example 4.

(Example 10)

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

(Example 11)

Except having used copolymerization PEN2 as thermoplastic resin B, it carried out similarly to Example 4, and obtained the laminated|multilayer film. The obtained laminated film exhibited the physical properties shown in Table 2, and showed a high Young's modulus similarly to Example 4. On the other hand, since the difference in glass transition temperature between the crystalline polyester and the thermoplastic resin B is small, the reflective performance is on the same level as that of Example 1. When this laminated film is processed into a product, it can be produced continuously with high precision and stably, and can be used without any problem in actual use.

(Example 12)

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

(Example 13)

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

(Example 14)

After the biaxial stretching, except that the speed of stretching the film in the longitudinal direction was 400%/sec, it carried out similarly to Example 13, and obtained the laminated film. The obtained laminated film exhibited the physical properties shown in Table 3, and exhibited a high Young's modulus. This laminated film can be produced continuously when it is processed into a product, and can be used without any problem in actual use. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarized light reflection performance was excellent.

(Example 15)

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

(Example 16)

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

(Example 17)

As the thermoplastic resin B, one obtained by copolymerizing 80 mol% of 2,6-naphthalene dicarboxylic acid and 20 mol% of isophthalic acid as the dicarboxylic acid component and ethylene glycol as the diol component with a glass transition temperature of 103°C was used. Except for copolymerizing PEN (copolymerizing PEN6), it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film exhibited the physical properties shown in Table 3, and exhibited a high Young's modulus. This laminated film can be produced continuously when it is processed into a product, and can be used without any problem in actual use. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarized light reflection performance was excellent.

(Example 18)

As the thermoplastic resin B, a glass transition temperature of 103°C was used, which was copolymerized using 70 mol% of 2,6-naphthalene dicarboxylic acid and 30 mol% of 1,8-naphthalene dicarboxylic acid as the dicarboxylic acid component, and ethylene glycol as the diol component. A laminated film was obtained in the same manner as in Example 4 except for the obtained copolymerized PEN (copolymerized PEN7). The obtained laminated film exhibited the physical properties shown in Table 3, and exhibited a high Young's modulus. This laminated film can be produced continuously when it is processed into a product, and can be used without any problem in actual use. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarized light reflection performance was excellent.

(Example 19)

As the thermoplastic resin B, copolymerized PEN obtained by copolymerizing 70 mol% of 2,6-naphthalene dicarboxylic acid and 30 mol% of 2,3-naphthalene dicarboxylic acid and ethylene glycol as the glycol component with a glass transition temperature of 103°C was used. (copolymerized PEN8), except that, it carried out similarly to Example 4, and obtained the laminated film. The obtained laminated film exhibited the physical properties shown in Table 3, and exhibited a high Young's modulus. This laminated film can be produced continuously when it is processed into a product, and can be used without any problem in actual use. In addition, the extinction ratio showing polarization characteristics was higher than that of Example 4, and the polarized light 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 exhibited the physical properties shown in Table 2, and exhibited a high Young's modulus similarly to Example 4. On the other hand, since it does not have a laminated structure, it does not exhibit specific reflective performance, and the film becomes brittle compared with the film of Example 1, so the handleability deteriorates. In this film, film breakage occurred during processing 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 exhibited the physical properties shown in Table 2, and, similarly to Example 1, exhibited a high Young's modulus in the film longitudinal direction. On the other hand, since the number of layers was as small as 3 layers, the reflection performance specific to the laminated structure was not exhibited, and the film was weaker than the film of Example 1, so the handleability was slightly lowered. In this laminated film, film breakage occurs during processing into a product, and continuous productivity is 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 4.5 times in the longitudinal direction of the film with rolls set at a temperature of 135°C. Then let it cool for a while.

The uniaxially stretched film obtained as above is 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 transported to Heat treatment was performed in an oven heated to 220°C. By trimming both ends of the obtained biaxially stretched film, a target laminated film was obtained as a film roll having a film width of 1500 mm and a length of 200 m.

The obtained laminated film exhibited the physical properties shown in Table 2, and compared with Example 4, the Young's modulus decreased. In this laminated film, film breakage occurs during processing into a product, and continuous productivity is 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 the length of the film. Both ends were thus obtained in a roll form with a film width of 2000 mm to obtain a 200 m target laminated film.

The obtained laminated film exhibited the physical properties 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 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 occurs during processing into a product, and continuous productivity is poor.

(comparative example 5)

The cast film obtained in the same manner as in Example 4 was heated with a roll set at a temperature of 120°C, and stretched 4.0 times in the longitudinal direction of the film with a roll set at a temperature of 135°C. , was trimmed, thereby obtaining a film roll formed of laminated films with a film width of 500 mm and a length of 200 m as intended.

The obtained laminated film exhibited the physical properties shown in Table 2, and compared with Example 4, the Young's modulus decreased. In addition, the reflective performance was also significantly lowered compared with the examples in accordance with the orientation of the thermoplastic resin B during stretching. In this laminated film, film breakage occurs during processing into a product, and continuous productivity is poor.

[Table 1]

Table 1

[Table 2]

[table 3]

Claims (14)

1. A laminated film, characterized in that it is formed by alternately laminating a layer A formed of a crystalline polyester and a layer B formed of a thermoplastic resin different from the crystalline polyester, totaling 11 or more layers, the The Young's modulus in the orientation axis direction of the laminated film is 6 GPa or more. 2. The laminated film according to claim 1, characterized in that, in the 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 the maximum reflectivity and the direction perpendicular to it The peak intensity I min ratio Imax/I min is 5 or more. 3. The laminated film according to claim 1, wherein the carboxylic acid component constituting the crystalline polyester contains 90 mol% or more of naphthalene dicarboxylic acid. 4. The laminated film according to claim 1 or 2, wherein linear expansion at a temperature of 40° C. to 50° C. The absolute value of the coefficient is 10 ppm/°C or less. 5. The laminated film according to claim 1 or 2, wherein the reflectance when the incident angle of the polarized light component parallel to the plane of incidence including the orientation axis direction is 10° is denoted as R1, and When the incident angle of the polarized light component perpendicular to the plane of incidence that includes the orientation axis direction is 10°, the reflectance is denoted as R2, and the reflectance at a wavelength of 550 nm satisfies the following formula (2) and formula (3 ), ·R2(550)≤40% (2) · R1(550) ≥ 70% (3). 6. The laminated film according to claim 1 or 2, in the first heating curve obtained by differential calorimetry DSC, the laminated film has a melting peak, and when the peak temperature of the melting peak is denoted as Tm, It has an exothermic peak in the range of Tm-110°C or higher and Tm-60°C or lower. 7. The laminated film according to claim 1 or 2, wherein 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 2 or more. 8. The laminated film according to claim 1 or 2, wherein the thermal shrinkage stress at a temperature of 100° C. in the orientation axis direction is 1 MPa or less. 9. The laminated film according to claim 1 or 2, wherein the absolute value of TMA at a temperature of 100° C. in the orientation axis direction is 0.5% or less. 10. The laminated film according to claim 1 or 2, wherein the melting peak derived from the thermoplastic resin B measured by differential scanning calorimetry (DSC) is 5 J/g or less. 11. The laminated film according to claim 1 or 2, wherein the A layer and the B layer satisfy the following conditions, · A layer: formed of aromatic polyester mainly composed of a dicarboxylic acid component and a diol component, 80 to 100 mol% of the 100 mol% of the dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, and the 80-100 mol% of 100 mol% of the diol component is ethylene glycol; · B layer: formed of aromatic polyester mainly composed of dicarboxylic acid components and diol components, 40 to 75 mol% of 100 mol% of the dicarboxylic acid components are 2,6-naphthalene dicarboxylic acid, 25 to 60 mol% is at least one component selected from isophthalic acid, 1,8-naphthalene dicarboxylic acid and 2,3-naphthalene dicarboxylic acid, and 80-100 mol% of the 100 mol% of the diol component is ethylene glycol. 12 . A film roll formed by winding the laminated film according to claim 1 along an orientation axis of the laminated film. 13 . 13. The film roll according to claim 12, wherein the laminated film has a width of 1000 mm or more. 14. A method for producing a laminated film, wherein a layer A formed of a crystalline polyester and a layer B formed of a thermoplastic resin different from the crystalline polyester are alternately laminated to a total of 11 or more layers. Stretch the film, stretch it along the length direction of the film at a ratio of 2 to 5 times, then stretch it along the width direction of the film at a ratio of 2 to 5 times, and then stretch it along the length direction of the film at a ratio of 1.3 to 4 times stretch.