TWI691405B - Laminated film and its manufacturing method - Google Patents

Abstract

The present invention provides a laminated film, which has various functions as a laminated film, and has high mechanical strength, and can be processed with high yield and high accuracy in various processing steps.

The laminated film of the present invention is characterized in that it is a laminated film composed of a total of 11 or more layers of alternating layer A including a layer A of crystalline polyester and a layer B of a thermoplastic resin different from the crystalline polyester. The Young's coefficient in the direction of the alignment axis of the film (the direction in which the Young's coefficient becomes maximum) is 6 GPa or more.

Description

Laminated film and its manufacturing method

The invention relates to a laminated film and a manufacturing method thereof.

Thermoplastic resin film, especially biaxially stretched polyester film, because of its excellent mechanical properties, electrical properties, dimensional stability, transparency and chemical resistance, etc., and in magnetic recording materials or packaging materials, etc. It can be widely used as a base film in many applications.

On the other hand, among polyester films, laminated films in which different resins are alternately laminated are used. As described above, the laminated film can be used as a film having a special function that cannot be obtained in a single-layer film, and examples thereof include a tear-resistant film with improved tear strength (see Patent Document 1), and infrared reflection that reflects infrared rays. A thin film (refer to Patent Document 2), a polarizing reflective film having polarizing reflection characteristics (refer to Patent Document 3), and the like.

However, in such a laminated film, since different resins are alternately laminated, the mechanical strength or dimensional stability tends to decrease due to the influence of the thickness of the laminate as compared with a single-layer film. When the mechanical strength or dimensional stability of the laminated film decreases, for example, when it is combined with various other films or components to perform punching, cutting, coating, and lamination of the functional film, the force applied to the film occurs And deformation or cracking occurs, and the processing accuracy during processing Or problems such as a decrease in the yield, and the optical characteristics or quality of the obtained film, or in fact, a problem that may occur due to a dimensional change when mounted on a product or the like.

Prior technical literature Patent Literature

Patent Literature 1 Japanese Patent No. 3960194

Patent Document 2 Japanese Patent No. 4310312

Patent Document 3 Japanese Patent Application Publication No. 2014-124845

Therefore, an object of the present invention is to provide a laminated film that can eliminate the above-mentioned problems, has various functions as a laminated film, and has high mechanical strength or dimensional stability, and can be produced in various processing steps with high yield It can be processed at a high rate/high precision without any defects in actual use.

The present invention is capable of solving the above-mentioned problems, and the laminated film of the present invention is characterized in that it is a layered layer consisting of a crystalline polyester and a layer B containing a thermoplastic resin different from the crystalline polyester. For a laminated film formed of 11 or more layers, the Young's coefficient in the direction of the alignment axis of the laminated film (the direction in which the Young's coefficient becomes maximum) is 6 GPa or more.

According to a preferred aspect of the laminated film of the present invention, in the 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 in which the reflectance becomes maximum and the The ratio I max/I min of the peak intensity I min in the orthogonal direction is 5 or more.

According to a preferred aspect of the laminated film of the present invention, the carboxylic acid component constituting the crystalline polyester contains 90 mol% or more of naphthalene dicarboxylic acid.

According to a preferred aspect of the laminated film of the present invention, in any of the direction of the alignment axis of the layered film and the direction orthogonal to the direction of the alignment axis, the coefficient of linear expansion at a temperature of 40°C or more and 50°C or less The absolute value is below 10ppm/℃.

According to a preferred aspect of the laminated film of the present invention, for the polarized light component parallel to the incident plane including the alignment axis direction of the laminated film, the reflectance at an incident angle of 10° is taken as R1, and The polarization component perpendicular to the incident surface in the direction of the alignment axis, when the reflectance at an incident angle of 10° is taken as R2, the reflectance at a wavelength of 550 nm satisfies the following formula (2) and formula (3);

. R2(550)≦40%. . . (2)

. R1(550)≧70%. . . (3)

According to a preferred aspect of the laminated film of the present invention, in the first heating curve of the differential calorimetry (hereinafter DSC) of the laminated film, the laminated film has a melting peak, and the melting peak top temperature is taken as Tm, and It has an exothermic peak in the range of Tm-110℃ or higher and Tm-60℃ or lower.

According to a preferred aspect of the laminated film of the present invention, the ratio of the Young's coefficient in the direction of the alignment axis of the laminated film and the direction orthogonal to 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 alignment 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 alignment 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 melting peak derived from the thermoplastic resin B by differential scanning calorimetry (DSC) of the laminated film is 5 J/g or less.

According to a preferred aspect of the laminated film of the present invention, the A layer and the B layer satisfy the following conditions; Layer A: Aromatic polyester containing a dicarboxylic acid component and a diol component as main components, 80-100 mol% of 100 mol% of the dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, and the diol component 80-100mol% of 100mol% is ethylene glycol; Layer B: Aromatic polyester containing dicarboxylic acid component and diol component as main components, 40-75mol% of 100-mol% dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, 25-60mol% It is a component selected from at least one of the group consisting of isophthalic acid, 1,8-naphthalene dicarboxylic acid and 2,3-naphthalene dicarboxylic acid. The diol component of 100 mol% is 80-100 mol% is ethyl Diol.

According to a preferred aspect of the laminated film of the present invention, the laminated film can be taken up along the alignment axis of the laminated film to become 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 manufacturing a laminated film of the present invention is characterized in that it is an unstretched film in which a total of 11 layers or more are alternately laminated by alternately laminating a layer A containing a crystalline polyester and a layer B containing a thermoplastic resin different from the crystalline polyester. After the film is stretched at a rate of 2 to 5 times in the direction of the long side of the film, it is stretched at a rate of 2 to 5 times in the direction of the width of the film, and is again extended by 1.3 to 4 times in the direction of the long side of the film.

According to the present invention, a laminated film can be obtained, which has high mechanical strength or dimensional stability, and can be suitably used and used when processing or using as various functional films such as punching, cutting, coating, and lamination. It can be used without any bad phenomenon during installation.

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

[Forms for carrying out the invention]

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

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

Here, the crystalline polyester A refers specifically to differential scanning calorimetry (hereinafter sometimes referred to as DSC) in accordance with JIS K7122 (1999), and the resin is heated from 25°C at a temperature increase rate of 20°C/min ( Temperature rise rate 20°C/min) up to 300°C (1stRUN), after holding it in its state for 5 minutes, it is then cooled to a temperature below 25°C and then cooled rapidly, again at 25°C at a temperature increase rate of 20°C/min In the differential scanning calorimetry chart of 2ndRUN obtained by raising the temperature to 300°C, the heat of crystallization melting ΔHm obtained from the peak area of the melting peak is 15 J/g or more of polyester. More preferably, the heat of crystal fusion is 20 J/g or more, and particularly preferably 25 J/g or more.

In addition, the thermoplastic resin B shows optical characteristics or thermal characteristics different from the crystalline polyester A used in the A layer. Specifically, it refers to any one of the two orthogonal directions arbitrarily selected in the plane of the laminated film and the direction perpendicular to the plane, the refractive index difference is 0.01 or more, or in DSC, it shows Those with different melting points or glass transition temperatures of ester A.

In addition, the so-called alternating layering here means that the layer A and the layer B are layered in a regular arrangement in the thickness direction. For example, those stacked in a regular arrangement as indicated by A(BA)n (n is a natural number). As mentioned above, by alternately laminating such resins with different optical properties, it is possible to exhibit dry reflection that can reflect light of a wavelength designed according to the relationship between the difference in refractive index of each layer and the layer thickness.

In addition, by alternately laminating resins with different thermal characteristics, when manufacturing a biaxially stretched film, the alignment state of each layer can be highly controlled, and optical characteristics, mechanical characteristics, or heat shrinkage characteristics can be controlled.

As a preferable laminated form of the laminated film, there may be mentioned a layer A having a crystalline polyester A layer, a layer B containing a thermoplastic resin B different from the crystalline polyester A, and a layer containing a crystalline polyester A In the case of the C layer of the thermoplastic resin C different from the thermoplastic resin B. As in the aforementioned case, the layer C such as CA(BA)n, CA(BA)nC, and A(BA)nCA(BA)m may be the outermost layer or a structure laminated on the intermediate layer.

In addition, when the number of laminated layers is less than 11 layers, it affects various physical properties such as film-forming properties and mechanical properties of different thermoplastic resin laminates. Therefore, for example, the production of biaxially stretched film becomes difficult, and there are The possibility of occurrence of undesirable phenomena when the constituent elements are combined as a product.

On the other hand, in the case of the laminated film of the present invention, in the case of alternately laminating a total of 11 or more layers of the laminated film, it is compared with a laminated film having fewer than 11 layers, because each thermoplastic resin is uniformly provided Therefore, the film-forming properties or mechanical properties can be stabilized. In addition, according to the increase in the number of layers, there is a tendency to suppress the growth of the alignment in each layer. For example, in addition to the improvement of the tear resistance due to the interfacial tension, it becomes easy to control the mechanical properties or heat shrinkage properties. The specific optical characteristics of the interference reflection function. The number of laminated layers is preferably 100 layers or more, and more preferably 200 layers or more. When the film is laminated with 100 or more layers, wide-band light can be reflected with high reflectivity, and when laminated with 200 layers or more, for example, it can reflect almost all visible light with a wavelength of 400 to 700 nm. In addition, although there is no upper limit on the number of layers to be stacked, as the number of layers increases, the manufacturing cost increases with the enlargement and complexity of the manufacturing apparatus, so in reality, the practical range is within 10,000 layers.

In the laminated film of the present invention, the Young's coefficient in the direction of the alignment axis of the laminated film must be 6 GPa or more. Here, the direction of the alignment axis of the laminated film is the direction in which the Young's coefficient of the film is changed every 10° in the film surface, and the Young's coefficient is the direction in which the maximum becomes. The Young's coefficient is an index that indicates the necessary force during the initial deformation of the film. As the Young's coefficient becomes higher, it applies a force to the laminated film when it is used in processing steps such as punching, cutting, coating, and laminating, or when it is used as a functional film. At the same time, the deformation can be suppressed, and it becomes easy to suppress the processing defect accompanying the deformation of the film or the performance change during use.

The Young's coefficient in the direction of the alignment axis of the laminated film is preferably 8 GPa or more, and more preferably 10 GPa or more. Due to the increase in Young's coefficient, the laminated film becomes difficult to deform, for example, because the control range of processing conditions during processing such as punching, cutting, coating, and lamination becomes larger, not only can processing defects be suppressed, but also to improve the obtained products The performance is also useful. In order to improve the Young's coefficient, as will be described later, in addition to selecting the resin, it can be achieved by a method of manufacturing a thin film.

In addition, in the case of a single layer or a plurality of layers, when the Young's coefficient of the alignment axis direction of the laminated film is 6 GPa or more, the laminated film tends to become brittle due to the strength of the alignment of the resin, and the handleability also decreases Case.

On the other hand, according to the present invention, in a case where a layer film including a crystalline polyester A layer A and a layer B including a thermoplastic resin B different from the crystalline polyester A are alternately stacked, a total of 11 or more layers are formed, Even if the Young's coefficient is 6 GPa or more, it can be achieved by the interfacial tension at the lamination interface or the buffer effect of the B layer containing the thermoplastic resin B. The Young's coefficient is improved by impairing the processability, and in the processing steps such as punching, cutting, coating, and lamination, or when used as a functional film, the effect of suppressing deformation can be obtained when a force is applied to the lamination film.

Furthermore, in the laminated film of the present invention, the aspect in which the ratio of the Young's coefficient in the direction of the alignment axis of the laminated film and the direction orthogonal to the same plane is 2 or more is also a preferable aspect. Even when the ratio of the Young's coefficient is simply increased by the choice of resin or the manufacturing method of the film, the Young's coefficient has a limit in a laminated film having an equal Young's coefficient in the in-plane direction of the laminated film. The foregoing is because the Young's coefficient depends on the strength of the alignment of the resin constituting the laminated film. Therefore, how to strongly align the direction in which the Young's coefficient is to be increased will affect the magnitude of the Young's coefficient.

On the other hand, in the processing steps such as punching, cutting, coating and lamination, especially in the step of continuous processing using a roll-shaped film, the Young's coefficient in the longitudinal direction of the laminated film is increased to stabilize the processing step Make the system effective. Therefore, by making the ratio of the Young's coefficient of the direction of the alignment axis of the laminated film and the direction orthogonal to the same plane to 2 or more, the Young's coefficient on the side of the alignment axis can be further increased, and the direction in which the Young's coefficient becomes the largest The Young's coefficient (in the direction of the alignment axis of the laminated film) easily becomes 6 GPa or more. More preferably, the ratio of the Young's coefficient in the direction of the alignment axis of the laminated film and the direction orthogonal to the same plane is 3 or more. In this case, the Young's coefficient in the direction of the alignment axis of the laminated film also easily becomes 10 GPa or more .

In the laminated film of the present invention, in the 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 in which the reflectance becomes the maximum and the peak intensity I min in the direction orthogonal thereto I max/I min is preferably 5 or more. Here, the direction in which the reflectance becomes the maximum is relative to the incident surface of the laminated film, where the polarized light component is 0° and the incident angle is 0°, and when the reflectivity is measured by changing the direction every 10° in the surface of the laminated film, Indicates the direction of maximum reflectance.

In addition, the peak at a wavelength of 1390 cm ^-1 observed in polarized Raman spectroscopy is due to the CNC stretching bond belonging to the naphthalene ring, and the peak intensity I max in the direction in which the reflectance becomes maximum and the peak intensity I in the direction orthogonal thereto The ratio of min I max/I min can determine the alignment state of the naphthalene ring. The I max/I min at a wavelength of 1390 cm ^-1 is preferably 5.5 or more, and more preferably 6 or more.

When I max/I min at a wavelength of 1390 cm ^-1 is 5 or more, it means that the naphthalene ring is uniformly aligned, and as a result, the high alignment can be used to increase the Young's coefficient. The upper limit of I max/I min at a wavelength of 1390 cm ^-1 prevents alignment of the layer A containing the crystalline polyester A containing naphthalene dicarboxylic acid and the layer B containing the thermoplastic resin B different from the crystalline polyester A From the viewpoint of deterioration of the interlayer adhesion due to the increase in the difference in state or crystallinity, the upper limit value is preferably 20, more preferably 10, and particularly preferably 7 or less. The I max/I min at a wavelength of 1390 cm-1 can be adjusted by selecting the combination of the resins of the A layer and the B layer and the film forming conditions.

Furthermore, in the laminated film of the present invention, in the polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1615 cm ^-1 , the peak intensity I max in the direction in which the reflectance becomes maximum and the peak intensity I min in the direction orthogonal thereto A ratio of I max/I min of 4 or more is a preferred aspect.

The peak of 1615 cm ^-1 observed in polarized Raman spectroscopy is due to the peak intensity I max in the direction of C=C stretching bond belonging to the benzene ring and the reflectance becomes maximum and the peak intensity I in the direction orthogonal to it The ratio of min I max/I min can determine the alignment state of the benzene ring. The I max/I min at a wavelength of 1615 cm ^-1 is preferably 4.5 or more, and 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 ring is uniformly aligned, and as a result, a high alignment can be used to increase the Young's coefficient.

The upper limit of I max/I min at a wavelength of 1615 cm ^-1 prevents alignment of the layer A containing the crystalline polyester A containing naphthalene dicarboxylic acid and the layer B containing the thermoplastic resin B different from the crystalline polyester A From the viewpoint of deterioration of the interlayer adhesion due to the increase in the difference in state or crystallinity, the upper limit is preferably 20 or less, more preferably 10 or less, and particularly preferably 6 or less. The I max/I min at a wavelength of 1615 cm-1 can be adjusted by selecting the combination of the resin of the A layer and the B layer and the film forming conditions. The most suitable combination example is as described above.

Furthermore, in the laminated film of the present invention, 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 in which the reflectance becomes maximum and the peak intensity I min in the direction orthogonal thereto The ratio I max/I min is preferably 5 or more.

In the laminated film of the present invention, the absolute value of the linear expansion coefficient at a temperature of 40°C or more and 50°C or less must be 10 ppm/ in either the direction of the alignment axis of the layered film or the direction orthogonal to the direction of the alignment axis Below ℃. The coefficient of linear expansion is an index that indicates the easy changeability of the film size when the temperature is changed. It changes according to the absolute value of the coefficient of thermal expansion. It is small, and it can suppress the deformation of the film when the temperature of the laminated film changes during the processing steps such as punching, cutting, coating and laminating, or when it is used as a functional film, and it also becomes easy to suppress the processing defects accompanying the deformation of the film Or the performance changes during use.

It is preferable that the absolute value of the linear expansion coefficient is 5 ppm/°C or less in any one of the alignment axis direction of the laminated film and the direction orthogonal to the alignment axis direction. As the absolute value of the coefficient of thermal expansion 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 larger, so not only can processing defects be suppressed, but also the performance of the resulting product can be improved. It is also useful to suppress dimensional deformation during actual use. In order to reduce the absolute value of the thermal expansion coefficient, as will be described later, in addition to selecting the resin, it can also be achieved by a method of manufacturing a thin film.

In addition, in the case of a single layer or a plurality of layers, the absolute value of the linear expansion coefficient at a temperature of 40°C to 50°C in the direction of the alignment axis of the laminated film is 10 ppm/°C or less because of the alignment of the resin The strength of the film tends to be brittle, and the handleability may also decrease. On the other hand, according to the present invention, in the case where a layer film including a crystalline polyester A and a layer B including a thermoplastic resin B different from the crystalline polyester A are alternately stacked, a total of 11 or more layers are formed Even if the absolute value of the coefficient of linear expansion at a temperature of 40°C to 50°C is 10 ppm/°C or less, the interfacial tension at the lamination interface or the cushioning effect of the B layer containing the thermoplastic resin B does not impair the handleability The coefficient of linear expansion is reduced, and in the processing steps such as punching, cutting, coating, and lamination, or when it is used as a functional film, the effect of suppressing deformation can be obtained when a force is applied to the lamination film.

In addition, in the laminated film of the present invention, it is also preferable that the thermal shrinkage stress at a temperature of 100° C. in the alignment axis direction of the laminated film is 1 MPa or less. Thermal shrinkage stress is an index indicating the amount of force that acts in the direction in which the laminated film shrinks when the temperature is changed. By reducing the thermal shrinkage stress, deformation can be suppressed when heat is applied to the laminated film during use, and Suppresses poor processing or changes in properties of laminated films. More preferably, the thermal shrinkage stress at a temperature of 100° C. is 0.5 MPa or less. In this case, the thermal deformation of the laminated film can also be suppressed during the processing step or actual use.

In the laminated film of the present invention, the absolute value of TMA represented by the following formula (1) in the alignment axis direction of the laminated film is preferably 0.5% or less at a temperature of 100°C. In the following formula (1), L and ΔL each represent the length of the layered film in the direction of the alignment axis at a temperature of 25°C, and the displacement of the length of the layered film when the temperature is changed by the temperature of 25°C. TMA is an index indicating the ratio of shrinkage or elongation of the laminated film when the temperature is changed. By making the absolute value of TMA smaller, deformation can be suppressed when heat is applied to the laminated film during use, and processing defects or films can be suppressed. Performance changes. More preferably, the absolute value of TMA at a temperature of 100° C. is 0.5% or less. In this case, the thermal deformation of the film can also be suppressed during the processing step or actual use.

. TMA=|△L/L|×100%. . . (1)

In the present invention, the laminated film may be a film roll wound along the alignment axis of the laminated film. As described above, in the processing steps such as punching, cutting, coating, and lamination, especially in the step of continuously processing using a roll-shaped film, the Young's coefficient in the longitudinal direction of the laminated film is increased It is effective for the stabilization of the processing step. By obtaining a film roll wound along the alignment axis of the laminated film, using the laminated film of the present invention makes it easy to obtain a high-quality product when the product is obtained.

In order to obtain the film roll as described above, it is preferable that the formation angle of the alignment axis direction of the laminated film and the flow direction of the film manufacturing step be 10° or less. When the angle between the alignment axis direction of the laminated film and the flow direction of the film manufacturing step is 10° or less, by continuously winding the obtained laminated film into a roll shape, processing steps such as punching, cutting, coating and laminating In particular, in the step of continuous processing using a roll-shaped film, since the direction of the alignment axis and the flow direction of the processing step become the same, it becomes easy to stabilize the processing step.

In fact, the winding direction of the film roll can be regarded as the flow direction of the film manufacturing step. In an actual product, the angle between the alignment axis direction of the laminated film and the winding direction of the film roll becomes 10° or less.

In the laminated film of the present invention, it is preferable that the layer A containing the crystalline polyester A is the outermost layer. In this case, the crystalline polyester A becomes the outermost layer, so it can be produced in the same manner as the crystalline polyester film such as polyethylene terephthalate film or polyethylene naphthalate film, and a biaxially stretched film can be produced. When the thermoplastic resin B that contains no crystalline polyester, for example, the amorphous resin contains the outermost layer, it is carried out in the same way as the crystalline polyester film to obtain a biaxially stretched film. In the case of problems such as poor film formation caused by adhesion of manufacturing equipment, or deterioration of surface properties.

As the crystalline polyester A used in the present invention, a polyester obtained by polymerizing a monomer containing an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol as a main component is preferably used.

Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2, 6- naphthalene dicarboxylic acid, 4,4 '- diphenyl dicarboxylic acid, 4,4' - diphenyl ether dicarboxylic acid, 4,4 '- diphenyl sulfone dicarboxylic acid. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexane dicarboxylic acid, and ester derivatives thereof. Only one type of these acid components may be used, or two or more types may be used in combination.

In particular, as the carboxylic acid component constituting the crystalline polyester A used in the laminated film of the present invention, from the viewpoint of exhibiting a high refractive index and improving the Young's coefficient, it is preferable to use terephthalic acid and 2,6-naphthalene Dicarboxylic acid. Terephthalic acid or 2,6-naphthalene dicarboxylic acid contains an aromatic ring with high symmetry, so by performing alignment and crystallization, it becomes easy to have both a high refractive index and a high Young's coefficient. In particular, when the carboxylic acid component constituting the crystalline polyester A includes 2,6-naphthalene dicarboxylic acid, by increasing the volume ratio of the aromatic ring, a high Young's coefficient can be achieved and it is commercially available in general, so it can be As a low-cost product.

Even more preferably, the carboxylic acid component constituting the crystalline polyester contains 80 mol% or more of 2,6-naphthalene dicarboxylic acid. According to containing 80 mol% or more of naphthalene dicarboxylic acid, during the manufacture of the laminated film, by performing stretching and heat treatment, alignment crystallization can be easily performed, and the Young's coefficient can be easily increased.

In addition, examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1 ,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, Sanyi Glycol, polyalkylene glycol, 2,2-bis(4-hydroxyethoxyphenyl) propane, isosorbide, spiroglycerin, etc. Among them, from the viewpoint of ease of polymerization, ethylene glycol is the main component and is preferred.

Here, the main component means 80 mol% or more of the diol component. More preferably, it is 90 mol% or more. Only one type of these diol components may be used, or two or more types may be used in combination. Oxygenated acids such as hydroxybenzoic acid can also be partially copolymerized.

As the thermoplastic resin B used in the present invention, chain polyolefins such as polyethylene, polypropylene, and poly(4-methylpentene-1) can be used; ring-opening displacement polymerization and addition polymerization of norbornene Alicyclic polyolefin as an addition copolymer with other olefins; polyamide 6, aramid, polymethyl methacrylate such as nylon 6, nylon 11, nylon 12, nylon 66, etc. , Polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymerized polymethacrylate Ester, polycarbonate; polytrimethylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polylactic acid, poly Polyesters such as butyl succinate; polyether ash, polyether ether ketone, modified polyphenylene ether, polyphenylene sulfide, polyether amide imine, polyimide, polyarylate, tetrafluoroethylene resin, Trifluoroethylene resin, chlorotrifluoroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, etc.

Among these, in addition to the viewpoints of strength, heat resistance, transparency, and versatility, from the viewpoint of adhesion and lamination with the crystalline polyester A used in the layer A, polyester is preferably used. Whether these are copolymers or mixtures, they can be used.

In the laminated film of the present invention, when the thermoplastic resin B is a polyester, it is preferable to use a monomer having an aromatic dicarboxylic acid component and/or an aliphatic dicarboxylic acid component and a diol component as main constituent components Polymerized polyester. Here, as the aromatic dicarboxylic acid component, the aliphatic dicarboxylic acid component, and the diol component, those listed for 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 having an aromatic dicarboxylic acid component and a diol component as main components. In particular, 40 to 75 mol% of the dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, and 25 to 60 mol% is selected from the group consisting of isophthalic acid, 1,8-naphthalene dicarboxylic acid and 2,3- Among the components of the naphthalene dicarboxylic acid group, 80 to 100 mol% of the 100 mol% of the diol component is ethylene glycol, which is a better form.

Isophthalic acid, 1,8-naphthalene dicarboxylic acid and 2,3-naphthalene dicarboxylic acid have an effect of bending molecular chains according to their molecular skeletons. As a result, the crystallinity or extension of the thermoplastic tree B can be achieved The alignment is reduced. As a result, it is possible to suppress an increase in the refractive index accompanying the alignment crystallization of the B layer when manufacturing the stretched film, and it is possible to make the refractive index difference from the A layer containing the crystalline polyester A (in the case of polarized reflection performance, the The refractive index difference of the alignment axis) is easily generated. As a result, especially when the polarization reflection characteristics are exhibited, higher optical characteristics can be exhibited.

In order to obtain a laminated film having a dry reflection function, as the thermoplastic resin B, an amorphous resin is also a preferable aspect. Compared to crystalline resins, amorphous resins are less likely to produce alignment during the manufacture of biaxially stretched films. The increase in the refractive index of the alignment crystallization of the layer B can easily cause the difference in refractive index from the layer A containing the crystalline polyester A. Especially when a heat treatment step is provided at the time of manufacturing the stretched film, this effect becomes remarkable.

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

Here, the term "amorphous resin" means that the resin is heated from 25°C (temperature rise rate 20°C/min) up to a temperature of 300°C (1stRUN) at 25°C/min at a temperature rise rate of 20°C/min in accordance with JIS K7122 (1999). After maintaining its state for 5 minutes, it was then cooled to a temperature of 25°C or less and then cooled rapidly. The temperature was raised from room temperature to 300°C again at a temperature increase rate of 20°C/min. The heat of crystal melting ΔHm determined from the peak area of the melting peak is 5 J/g or less, and more preferably a resin that does not show a peak corresponding to crystal melting.

In addition, in order to obtain a laminated film having a dry reflection function, as the thermoplastic resin B, a crystalline resin having a melting point lower than the melting point of the crystalline polyester A by 20° C. or higher is also preferably used. In this case, in the heat treatment step, by performing the heat treatment at a temperature between the melting point of the thermoplastic resin B and the melting point of the crystalline polyester A, the heat treatment step can be completely relaxed, and the crystalline polyester can be included. The refractive index difference of the A layer of A is maximized. Preferably, the difference between the melting points of the crystalline polyester A and the thermoplastic resin B is 40°C or higher. In this case, since the selection range of the temperature in the heat treatment step becomes wider, it is possible to more easily promote the alignment of the thermoplastic resin B or control the alignment of the crystalline polyester.

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 the two is preferably 1.0 or less. When the absolute value of the difference between the SP values becomes 1.0 or less, it is difficult to cause delamination between the A layer and the B layer. More preferably, the combination of the crystalline polyester A and the thermoplastic resin B includes the same basic skeleton.

The basic skeleton here is a repeating unit constituting the resin. For example, as the crystalline polyester A, polyethylene naphthalate containing only 2,6-naphthalene dicarboxylic acid as the carboxylic acid component or 80% or more of the carboxylic acid component is used as 2,6-naphthalene dicarboxylic acid When the polyethylene naphthalate copolymer as the main component is used as the thermoplastic resin B, a crystal with a lower melting point than the amorphous polyethylene naphthalate copolymer or crystalline polyester A is used. The preferred polyethylene naphthalate copolymer is preferred.

In addition, in order to obtain a laminated film having a dry reflection function, the glass transition temperature of the thermoplastic resin B is preferably 10° C. or more lower than the glass transition temperature of the crystalline polyester A. In this case, in the stretching step, when the most suitable stretching temperature is adopted in order to stretch the crystalline polyester, since the orientation of the thermoplastic resin B does not progress, it can be refracted with the layer A containing the crystalline polyester The rate difference becomes larger. More preferably, the glass transition temperature of the thermoplastic resin B is more than 20°C lower than the glass transition temperature of the crystalline polyester A.

In order to obtain a suitable manufacturing method for the laminated film of the present invention described later, the orientation crystallization of the thermoplastic resin B may easily progress and the desired dry reflection function may not be obtained. The glass transition temperature of the plastic resin B is lower than the glass transition temperature of the crystalline polyester A by more than 20°C, which can suppress the alignment crystallization.

In addition, various additives can be added to the thermoplastic resin without deteriorating its characteristics, for example, antioxidants, heat-resistant stabilizers, weather-resistant stabilizers, ultraviolet absorbers, organic slip agents, pigments, dyes, organic or Inorganic particles, fillers, antistatic agents, and nucleating agents.

In the laminated film of the present invention, for the polarized light component parallel to the incident surface in the direction of the alignment axis including the laminated film, the reflectance at an incidence angle of 10° is taken as R1, and for the alignment axis with respect to the alignment axis including the laminated film When the polarized light component perpendicular to the incident surface in the direction is R2, and the reflectance at an incident angle of 10° is R2, the reflectance at a wavelength of 550 nm preferably 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 any polarized light and transmit the other polarized light.

In order to obtain a film satisfying the following formula (2), it can be adjusted according to a combination of resins having a refractive index difference between the A layer and the B layer in the alignment axis direction of the laminated film to be 0.02 or less, more preferably 0.01 or less, particularly preferably 0.005 or less. In addition, in order to obtain a film satisfying the following formula (3), a combination of resins with a refractive index difference between the A layer and the B layer in the direction orthogonal to the alignment axis direction of the laminated film of 0.08 or more and film formation may be used Conditions are adjusted, more preferably 0.1 or more, particularly preferably 0.15 or more. Examples of the most suitable combination are as described above.

. R2(550)≦40%. . . (2)

. R1(550)≧70%. . . (3).

In the laminated film of the present invention, in the first temperature rise curve of the DSC, the laminated film has a melting peak Tm, and at the top temperature of its melting peak It is preferable that the range of Tm-110°C or higher and Tm-60°C or lower has an exothermic peak. On the premise of exhibiting the above-mentioned polarization characteristics, the refractive index control of each layer becomes important, and the control of alignment and crystallinity becomes important. In its control, the layer A containing the crystalline polyester A can be made to have a high degree of alignment in one direction to increase the difference in refractive index between the alignment direction and the direction perpendicular thereto. In contrast, the B layer must be consistent with either of the refractive indexes of the A layer (mainly in the direction of low refractive index), and the difference in refractive index with the other (mainly in the direction of high refractive index) becomes larger, controlling the B layer The alignment or crystallinity is important.

As a result of careful investigation by the inventors of the present case, it was found that, as an indicator of B layer control, in the first heating curve of DSC, the laminated film has a melting peak Tm, and at the melting peak top temperature Tm-110°C or more Tm-60°C The following range has an exothermic peak, and high optical characteristics can be obtained.

This exothermic peak is a peak indicating exothermic heat due to crystallization of the B layer, and accordingly, is an index of the alignment and crystallinity of the B layer. When this exothermic peak does not exist, the alignment crystallization of layer B progresses during the film formation step, or the crystallinity is extremely low. Therefore, the relationship between the refractive index of layer A and the layer A is not within the desired range, and the optical characteristics are degraded.

In addition, even if an exothermic peak exists, if it exceeds Tm-110°C or higher and Tm-60°C or lower, the relationship between the refractive index of the layer A and the layer B will be excessively oriented, exhibit anisotropy, or the crystallinity becomes extremely low, etc. Not in the desired range, but the optical characteristics are degraded. Therefore, in the laminated film of the present invention, on the premise of obtaining high optical characteristics, it is necessary to have an exothermic peak in the range of Tm-110°C or higher and Tm-60°C or lower.

As a method of producing a laminated film having an exothermic peak at Tm-110°C or higher and Tm-60°C or lower, the following may be mentioned: the A layer and the B layer In the manufacturing method described later, the temperature, the magnification, and the elongation speed in the elongation step are within the preferred ranges. These methods should also be combined in multiples.

In the laminated film of the present invention, it is preferable that the heat release amount of the heat release peak is 0.1 J/g or more and 10 J/g or less. The heat release amount is more preferably 0.5J/g or more and 5J/g or less, and particularly preferably 1.5J/g or more and 4J/g or less. When the exotherm exceeds Tm-110°C and Tm-60°C or less, the B layer will be over-aligned, exhibit anisotropy, or the crystallinity becomes extremely low, etc., the relationship with the refractive index of the A layer is not within the required range, and Optical characteristics are degraded. In the laminated film of the present invention, by making the heat release amount of the heat release peak 0.1 J/g or more and 10 J/g or less, high optical characteristics can be obtained.

In the laminated film of the present invention, the melting peak temperature Tm is preferably 255°C or higher. The melting peak temperature is more preferably 258°C or higher. In order to satisfy the range of the melting peak temperature, a resin that is also a preferable range among the aforementioned resins can be mentioned. According to this, the optical characteristics can be improved, and a thin film with high heat resistance can be obtained.

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

In addition, the laminated structure of the laminated film used 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 can be dried in hot air or under vacuum if necessary, and then supplied to various extruders. In the extruder, the resin melted by heating is homogenized by a gear pump, etc. Filters, etc. remove foreign objects or modified resins. These resins are fed into a multi-layer stacking device.

As the multi-layer stacking device, a multi-manifold die, a feed head, a static mixer, or the like can be used, but in order to efficiently obtain the configuration of the present invention, it is preferable to use a feed head having 11 or more micro slits. By using the feed head as described above, the device will not be extremely large, so there are few foreign objects due to thermal degradation, and even if the number of layers is extremely large, it can be a layer with high accuracy. In addition, the lamination accuracy in the width direction is significantly improved compared to the conventional technology. Furthermore, in this device, since the thickness of each layer can be adjusted in the shape of a slit (length, width), an arbitrary layer thickness can be achieved.

Then, the laminated sheet discharged from the mold is extruded on a cooling body such as a casting drum, cooled and solidified to obtain a cast film. At this time, it is preferable to use electrodes in the form of a wire, a strip, a needle, or a knife, etc., and use electrostatic force to closely adhere the discharged sheet to the cooling body, and quench and solidify. In addition, as a method of making the discharged sheet closely adhere to the cooling body, a method of blowing air from a slit-shaped, dot-shaped, and planar device, and a method of using a roll are also preferred.

The cast film obtained as described above is preferably biaxially stretched. Here, biaxial stretching refers to stretching the film in the longitudinal direction and the width direction.

Furthermore, as a method for obtaining a proper biaxial stretching of the laminated film of the present invention, it is necessary to extend the film in the longitudinal direction at a magnification of 2 to 5 times, and then to the film in the width direction of 2 to 5 times, and again toward The film extends 1.3 to 4 times in the longitudinal direction. The details are described below.

First, the obtained cast film is extended in the longitudinal direction. The extension in the long-side direction is usually implemented by the difference in the circumferential speed of the roller. This stretching can be performed in one stage, and multiple stages can also be performed using multiple roller pairs. The stretching ratio varies depending on the type of resin, but it is preferably 2 to 5 times. The purpose of this first extension in the longitudinal direction is to provide the necessary minimum alignment in order to improve the uniform elongation during the subsequent extension in the width direction of the film. Therefore, when the stretching magnification is made larger than 5 times, when a film is stretched in the width direction to be described later, and when the film is stretched again in the longitudinal direction after the step, a film with a sufficient stretching magnification cannot be obtained. Case. In addition, when the stretching ratio is less than 2 times, the necessary minimum alignment cannot be provided during stretching, and the thickness unevenness may occur in the longitudinal direction of the film and the quality may deteriorate. In addition, as the elongation temperature, the temperature of the glass transition temperature of the crystalline polyester A constituting the laminated film to the glass transition temperature + 30°C is preferable.

After the uniaxially stretched film obtained as described above is subjected to surface treatments such as corona treatment, flame treatment, plasma treatment, etc., if necessary, it can be given smoothness, easy adhesion and antistatic properties by in-line coating. function.

Next, the uniaxially stretched film is stretched in the width direction. For stretching in the width direction, a tenter is usually used, and while holding both ends of the film with a jig, it is carried and stretched in the width direction. The stretching ratio varies depending on the type of resin, but it is usually preferably 2 to 5 times. The purpose of the extension in the width direction is to provide the minimum alignment required for the subsequent extension of the film in the longitudinal direction to give high extensibility. Therefore, if the extension magnification is greater than 5 times, then When the film is stretched again in the longitudinal direction of the film by this step, a film with a sufficient stretching ratio may not be obtained. In addition, when the stretching ratio is less than 2 times, uneven thickness may occur in the film width direction during stretching, and the quality may be deteriorated. In addition, the stretching temperature is preferably between the glass transition temperature of the crystalline polyester A constituting the laminated film ~ the glass transition temperature + 30°C, or the glass transition temperature ~ the crystallization temperature of the crystalline polyester.

Secondly, the obtained biaxially stretched film is stretched again in the long-side direction. The extension in the longitudinal direction of the pair is usually performed using the difference in the circumferential speed of the roller. This stretching may be performed in one stage, or may be performed in multiple stages using multiple roller pairs. The stretch magnification varies with the type of resin, but 1.3 to 4 times is better. The purpose of the second extension in the long-side direction is to align the film as strongly as possible in the long-side direction. As described above, by extending the long-side direction again, the resin will be strongly aligned. As a result, the laminated film can be made The linear expansion coefficient in the direction in which the Young's coefficient in the direction of the alignment axis becomes 6 GPa or more, or the direction where the Young's coefficient is maximized (in the direction of the alignment axis of the laminated film) becomes 10 ppm/°C or less. In particular, the higher the stretch magnification in the longitudinal direction, the higher the Young's coefficient, or the linear expansion coefficient can be suppressed, so that the Young's coefficient becomes 10 GPa or more, and the absolute value of the linear expansion coefficient of 40°C or more and 50°C or less becomes 5ppm/°C or lower also becomes easy. 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.

As described above, in order to impart flatness and dimensional stability to the biaxially stretched film, heat treatment is preferably performed in a tenter at a temperature above the stretching temperature and below the melting point. By performing heat treatment, the crystallization of alignment can be promoted and the effect of increasing the Young's coefficient can be obtained, along with the alignment The promotion of crystallization also improves the dimensional stability. As a result, in either the direction in which the Young's coefficient becomes the largest (the direction of the alignment axis of the laminated film) and the direction orthogonal to the direction of the alignment axis of the laminated film, 40 The absolute value of the coefficient of linear expansion at a temperature of ℃ to 50°C becomes 5 ppm/°C or less. In addition, the thermal shrinkage stress at a temperature of 100°C in the direction of the alignment axis may be 1 MPa or less, and the absolute value of TMA at a temperature of 100°C in the direction of the alignment axis may be 0.5% or less. After performing the heat treatment as described above, after uniformly slow cooling, cool to normal temperature and wind up. Furthermore, if necessary, after heat treatment, relaxation treatment or the like may be performed on the occasion of slow cooling.

The laminated film obtained by the above-mentioned manufacturing method can be made into a laminated film having not only a high Young's coefficient but also the polarization reflection characteristics satisfying the above formulas (2) and (3). This is because when the film is extended in the longitudinal direction for the second time, the alignment of the layer A containing crystalline polyester A can be made stronger in the longitudinal direction of the film. As a result, the refractive index in the longitudinal direction of the film and There is a difference in refractive index in the width direction of the film perpendicular to the longitudinal direction of the film. Furthermore, as the thermoplastic resin B, an amorphous resin, or a combination of a crystalline polyester A and a thermoplastic resin B that can ease the alignment of the glass transition temperature/melting point difference between the stretching step and the heat treatment step, With this, the orientation of the thermoplastic resin B can be suppressed, and polarized light reflection characteristics can be imparted.

(Measurement method of characteristics and evaluation method of effect)

The method for measuring the characteristics of the present invention and the method for evaluating the effects are as follows.

(1) Number of layers:

The layer configuration of the laminated film was obtained by observing a sample cut through a slicer using a transmission electron microscope (TEM). That is, using a transmission electron microscope model H-7100FA (manufactured by Hitachi, Ltd.), a cross-sectional photograph of the film was taken under the condition of an acceleration voltage of 75 kV, and the layer configuration and the thickness of each layer were measured. According to circumstances, in order to improve the contrast, a dyeing technique using RuO ₄ or OsO _{4 is} used. In addition, according to the thickness of the thinnest layer (thin film layer) among all the layers contained in one image, when the thickness of the thin film layer is less than 50 nm, the observation is performed at an enlargement magnification of 100,000 times. When it is 50 nm or more and less than 500 nm, the observation is carried out at a magnification of 40,000 times, and when it is 500 nm or more, the observation is carried out at a magnification of 10,000 times.

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

The TEM photo image obtained in the above item (1) was included in an image size of 720 dpi using a scanner (CANOSCAN D1230U manufactured by Canon Corporation). Save the image as a bit image file (BMP) or compressed image file (JPEG) on the personal computer. Secondly, use the image processing software Image-Pro Plus ver.4 (seller: Planetron (share)) to open Perform image analysis on the file. The image analysis process uses the vertical thick profile mode to read the relationship between the average brightness of the area sandwiched between the thickness direction position and the two lines in the width direction as numerical data.

Using a table calculation software (Excel 2000), relative to the position (nm) and brightness data, the sampling step 2 (thinning 2) is used for data adoption, and then a 5-point moving average numerical processing is implemented. Furthermore, differentiate the obtained data of periodic brightness changes, and use the VBA (Visual Basic for Applications) program to read the maximum value and minimum value of the differential curve Value, the interval between adjacent regions with extremely high luminance and extremely small regions is regarded as the layer thickness of one layer, and the layer thickness is calculated. Perform this operation for each photo to calculate the layer thickness and number of all layers.

(3) Young's coefficient:

The laminated film was cut into an elongated rectangle with a length of 150 mm × a width of 10 mm as a sample. Using a tensile testing machine (Tensilon UCT-100 manufactured by ORIENTEC), the distance between the initial tensile chucks was set at 50 mm, and the tensile speed was set at 300 mm/min to perform a tensile test. The measurement was carried out in an environment with a room temperature of 23°C and a relative humidity of 65%, and the Young's coefficient was obtained from the obtained load-strain curve. The measurement was performed 5 times for each sample, and the average value was evaluated.

(4) Alignment axis direction of laminated film:

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

(5) Coefficient of linear expansion:

The laminated film was cut into an elongated rectangle with a length of 25 mm × a width of 4 mm in the direction of its alignment axis as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the initial tensile chucks was set at 15 mm, the tensile tension was maintained at 29.4 mN, and the temperature in the testing machine was increased from 25°C to 5°C/min up to 150 At a temperature of ℃, TMA was measured in the direction of the alignment axis of the laminated film. The linear expansion coefficient at a temperature of 40°C to 50°C was determined from the obtained TMA-temperature curve. The coefficient of linear expansion is simultaneously determined from the difference between the TMA and the temperature and the value of ±5°C of the temperature to be measured.

(6) Thermal shrinkage stress:

The laminated film was cut into an elongated rectangle with a length of 25 mm × a width of 4 mm in the direction of its alignment axis as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the stretching chucks was kept fixed at 15 mm, and the temperature in the testing machine was increased from 25°C at 5°C/min up to 150°C. For the alignment axis of the laminated film The direction measures the heat shrinkage stress. The heat shrinkage stress was obtained from the obtained stress-temperature curve.

(7) TMA:

The laminated film was cut into an elongated rectangle with a length of 25 mm × a width of 4 mm in the direction of its alignment axis as a sample. Using a TMA testing machine (TMA/SS6000 manufactured by Seiko Instruments), the distance between the initial tensile chucks was set at 15 mm, the tensile tension was maintained at 29.4 mN, and the temperature in the testing machine was increased from 25°C to 5°C/min up to 150 At a temperature of ℃, TMA was measured in the direction of the alignment axis of the laminated film. TMA is obtained from the obtained TMA-temperature curve.

(8) Measurement of reflectance and transmittance relative to incident light with polarized light components:

The center of the alignment axis direction on the line segment where the length of the sample from the alignment axis direction becomes the largest is cut out to 5 cm×5 cm. A basic configuration using an integrating sphere attached to a spectrophotometer (U-4100 Spectrophotomater) manufactured by Hitachi, Ltd. was used, and the measurement was performed using the auxiliary white board of alumina attached to the device as a reference. In the sample, the direction of the alignment axis of the laminated film is set to the vertical direction, and it is placed behind the integrating sphere. In addition, an attached polarizer made by Glan Taylor was installed, and linearly polarized light having polarized components of 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 is set to 2nm (visible light)/automatic control (infrared), the gain is set to 2, the scanning speed is measured at 600nm/min, and the reflectance at an azimuth angle of 0 to 180 degrees is obtained. During the reflection measurement of the sample, because the interference caused by the reflection from the back disappears, it is painted black with Magic Ink (registered trademark).

In addition, the samples cut out in the same way were not painted black, and the transmittance was measured in the same manner. From the obtained transmittance data, the extinction ratio at a wavelength of 550 nm was determined according to the following formula.

. Extinction ratio = T2/T1

(Here, T1 represents the transmittance of the polarized light component parallel to the incident surface in the direction of the alignment axis containing the laminated film at an incident angle of 0°, and T2 represents the perpendicular to the incident surface in the direction of the alignment axis containing the laminated film Polarized light component, transmittance at an incident angle of 0°.)

(9) Peak intensity ratio I max/I min of polarized Raman spectrum:

Polarized Raman spectroscopy was measured using laser Raman spectrometer T-64000 manufactured by Jovin Yvon. For a laminated film, take the direction where the reflectivity determined by the above item (4) becomes the maximum as I max and the direction orthogonal to it as I min, and make the cross-section in each direction into the measurement surface and cut the cross-section with a microtome . Polarized Raman spectroscopy is measured from the sample cross section, and the case where the polarization axis of the laser coincides with the transmission axis of the film is measured as a parallel condition, and the case where it coincides with the thickness direction of the laminated film is measured as a vertical condition. For the measurement, the center of each layer was changed at three points, and the average value was used as the measured value. The detailed measurement conditions are as follows.

. Measurement mode: Micro Raman

. Object lens: ×100

. Beam diameter: 1μm

. Cross seam: 100μm

. Light source: Ar+laser/514.5nm

. Laser power: 15mW

. Diffraction grating: Spectrograph 600gr/mm

. Dispersion: Single 21Å/mm

. Seam: 100μm

. Detector: CCD/Jobin Yvon 1024×256.

The peak intensity ratio of the polarized Raman spectrum at a wavelength of 1390 cm ^-1 and the wavelength of 1615 cm ^-1 is I max/I min. For the peak intensity of 1390 cm ^-1 of the CNC stretching bond derived from the naphthalene ring obtained by the measurement of the polarized Raman spectrum , And, the peak intensity of 1615 cm ^-1 derived from the C=C stretch bond of the benzene ring is calculated from the peak intensity of the sample with the measurement surface as the profile in the I max direction and the sample with the measurement surface as the profile in the I min direction ratio.

(10) Melting enthalpy and glass transition temperature:

The laminated film was sampled from the measurement, and using differential calorimetry (DSC), the DSC curve of the measurement sample was measured in accordance with JIS-K-7122 (1987). In the test, the temperature was raised from 25°C at 20°C/min up to 290°C, and the melting enthalpy and glass transition temperature at this time were measured. The equipment used is as follows.

. Device: "robot DSC-RDC220" manufactured by Seiko Electronics Industry Co., Ltd.

. Data analysis "disk session SSC/5200"

. Sample quality: 5mg.

(11) Workability:

The roll-shaped film was introduced into a punching machine, the length was set to 500 mm, and a rectangular mold with a width of 95% of the width was used for punching with respect to the width of the film. In addition, the punching interval in the longitudinal direction is set to 40 mm. The following A, B, and C evaluations were performed. Pass A and B as qualified.

A: The film is not broken, and can be continuously transported and processed.

B: Although the film causes partial cracking, it can be continuously transported in the longitudinal direction and can be processed continuously.

C: The film was completely broken, and the long-side direction could not be processed continuously.

(12) Installation test:

The laminated film to be the sample was cut out from the position in the center in the width direction of the film in the longitudinal direction of 1450 mm × the width of 820 mm. Then, on the 32-type LCD TV LHD32K15JP backlight manufactured by HISENSE JAPAN Co., Ltd., in the order of 50% diffusion plate, microlens sheet, polarized reflector, and polarizing plate, and based on the temperature of 50 ℃ and 85 ℃, by The flatness of the polarizing reflector after the 12-hour heat resistance test was visually evaluated.

The evaluation of flatness is judged by the following A, B and C. Pass A as a pass.

A: At 50℃ and 85℃, there is no appearance problem

B: At a temperature of 50°C, there is a problem of appearance.

(13) The content of naphthalene dicarboxylic acid:

The layer A of the laminated film containing the crystalline polyester was dissolved in deuterated hexafluoroisopropanol (HFIP) or a mixed solvent of HFIP and deuterated chloroform, and the 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. Also, as the thermoplastic resin B, an amorphous resin having no melting point and 25 mol% of 2,6-naphthalene dicarboxylic acid spiroglycerin and 25 mol% of terephthalic acid with a glass transition temperature of 103°C, and Copolymerized PEN copolymerized with 50 mol% of ethylene glycol (copolymerized PEN1).

The prepared crystalline polyester A and thermoplastic resin B were separately put into two uniaxial extruders, melted and kneaded at a temperature of 290°C. Next, after the crystalline polyester A and the thermoplastic resin B were separated by five FSS disc filters, they were combined with a lamination device with 11 slits while being measured by a gear pump to obtain a thickness direction. The 11-layer laminate is alternately stacked. The method of becoming a laminate can be performed according to the method described in paragraphs [0053] to [0056] of Japanese Patent Laid-Open No. 2007-307893.

Here, the length and interval of the seam are all fixed. The obtained laminate has 6 layers of crystalline polyester A and 5 layers of thermoplastic resin B, and has a layered structure in which layers are alternately stacked in the thickness direction. Furthermore, the value of the film width direction length of the lip of the lip of the widening ratio inside the ferrule divided by the film width direction length at the inflow portion of the ferrule was 2.5. The width of the cast film obtained was 600 mm.

The obtained cast film was heated by a roller group set at a temperature of 120°C, and then stretched 3.0 times in the longitudinal direction of the film at a temperature set at 135°C, and then temporarily cooled. Will be done as before The uniaxially stretched film was led to a tenter, preheated with hot air at a temperature of 115°C, and stretched 3.0 times in the width direction of the film at a temperature of 135°C to obtain a biaxially stretched film as a film roll. The width of the biaxially stretched film obtained here was 1500 mm.

Furthermore, after heating the biaxially stretched film with a roller set at a temperature of 120°C, the film is stretched 3.0 times in the longitudinal direction of the film at a temperature of 160°C, and both ends of the film are trimmed to obtain the target The laminated film of the object has a film width of 1000 mm and a length of 200 m.

The obtained laminated film showed the physical properties shown in Table 1, and showed a high Young's coefficient and a low linear expansion coefficient (40 to 50°C) in the MD direction. In addition, it exhibits dry reflection characteristics derived from refractive indexes different from those of the crystalline polyester A and the thermoplastic resin B. The laminated film of the present invention can also be used well when processing products or when actually used.

(Example 2)

The laminated film was obtained in the same manner as in Example 1, except that the layering device to be used was a device with 101 slits.

The obtained laminated film exhibited the physical properties shown in Table 1, and showed a high Young's coefficient and a low linear expansion coefficient (40 to 50°C) in the longitudinal direction of the film as in Example 1. In addition, it shows dry reflection characteristics derived from refractive indexes different from those of the crystalline polyester A and the thermoplastic resin B. Compared with Example 1, it also shows high polarized reflection characteristics. The laminated film is also highly accurate and stable in the processing of products and can be continuously produced, and it can be used without problems in actual use.

(Example 3)

The laminated film was obtained in the same manner as in Example 1, except that the layering device to be used was a device with 201 slits.

The obtained laminated film exhibited the physical properties shown in Table 1, and in the same manner as in Example 1, it exhibited a high Young's coefficient and a low linear expansion coefficient (40 to 50°C) in the MD direction. In addition, it exhibits dry reflection characteristics derived from refractive indexes different from those of the crystalline polyester A and the thermoplastic resin B. Compared with Example 2, it also shows high polarized reflection characteristics, which is a level that can be used as a polarized reflection member. The laminated film is also highly accurate and stable in the processing of products and can be continuously produced, and it can be used without problems in actual use.

(Example 4)

The laminated film was obtained in the same manner as in Example 1 except that the layering device to be used was a device with 801 slits. The obtained laminated film exhibited the physical properties shown in Table 1, and in the same manner as in Example 1, it exhibited a high Young's coefficient and a low linear expansion coefficient (40 to 50°C) in the MD direction. In addition, it shows dry reflection characteristics derived from refractive indexes different from those of the crystalline polyester A and the thermoplastic resin B. Compared with Example 3, it also shows high polarized reflection characteristics, and has very high performance as a polarized reflection member. The laminated film is also highly accurate and stable in the processing of products and can be continuously produced, and it can be used without problems in actual use.

(Example 5)

A laminated film was obtained in the same manner as in Example 4 except that the magnification when the biaxially stretched film was stretched again in the longitudinal direction of the film was 2.5 times. The resulting laminated film showed the materials shown in Table 1. It shows high Young's coefficient and low linear expansion coefficient (40~50℃). In addition, as in Example 4, it exhibits high polarization reflection characteristics, and has very high performance as a polarization reflection member. The laminated film is also highly accurate and stable in the processing of products and can be continuously produced, and it can be used without problems in actual use.

(Example 6)

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

(Example 7)

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

(Example 8)

After the biaxially stretched film was stretched again in the long-side direction, it was carried out in the same manner as in Example 4 except that it was transported in an oven heated to a temperature of 180°C and subjected to heat treatment to obtain a laminated film. The obtained laminated film showed the physical properties shown in Table 1, and exhibited a high Young's coefficient and a low linear expansion coefficient (40 to 50°C). In addition, as in Example 4, highly polarized light is displayed The reflection characteristic is very high performance as a polarized reflection member. Furthermore, compared with Example 4, the obtained film can also suppress the absolute value of heat shrinkage stress and TMA at 100°C in the longitudinal direction of the film to be low. The laminated film processed the product under specific conditions At the same time, it is stable with high accuracy and can be continuously produced, and in actual use, it can be used without problems under more severe conditions than in Example 4.

(Example 9)

After the biaxially stretched film was stretched again in the long-side direction, it was carried out in the same manner as in Example 4 except that it was transported in an oven heated to a temperature of 220°C and subjected to heat treatment to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 2 and exhibited a high Young's coefficient and a low linear expansion coefficient (40-50°C). In addition, as in Example 4, it exhibits high polarization reflection characteristics, and has very high performance as a polarization reflection member. Furthermore, compared with Example 4, the obtained film can also suppress the absolute value of heat shrinkage stress and TMA at 100°C in the longitudinal direction of the film to be low. The laminated film processed the product under specific conditions At the same time, it is stable with high accuracy and can be continuously produced, and in actual use, it can be used without problems under more severe conditions than in Example 4.

(Example 10)

In addition to the use of copolymerization PEN (copolymerization PEN2) which copolymerizes 2,6-naphthalene dicarboxylic acid 50 mol%, spiroglycerol 5 mol%, and ethylene glycol 45 mol% with a melting point of 240°C and a glass transition temperature of 118°C Except for the functional polyester, the same procedure as in Example 4 was carried out to obtain a laminated film. The obtained laminated film showed the physical properties shown in Table 2 and showed a high Young's coefficient. The laminated film can be continuously produced when the product is processed under specific conditions, and it can be used without problems in actual use.

(Example 11)

A laminated film was obtained in the same manner as in Example 4 except that copolymerized PEN2 was used as the thermoplastic resin B. The obtained laminated film exhibited the physical properties shown in Table 2, and showed a high Young's coefficient in the same manner as in Example 4. On the other hand, the difference between the glass transition temperature of the crystalline polyester and the thermoplastic resin B is small, and the reflection performance is the same as that of Example 1. The laminated film is also highly accurate and stable in the processing of products and can be continuously produced, and it can be used without problems in actual use.

(Example 12)

In addition to the use of polyethylene terephthalate (PET) with a melting point of 256°C and a glass transition temperature of 81°C as the crystalline polyester, an amorphous resin with a glass transition temperature of 78°C is used Except for the thermoplastic resin B, methanol copolymerized PET (copolymerized PET) was carried out in the same manner as in Example 4 to obtain a laminated film. The obtained laminated film exhibited the physical properties shown in Table 2, and showed a higher Young's coefficient compared to Comparative Examples 1 to 5. The laminated film can be continuously produced when the product is processed 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 is lower than in Example 4.

(Example 13)

In addition to the copolymerization using 70 mol% of 2,6-naphthalene dicarboxylic acid and 30 mol% of isophthalic acid as the dicarboxylic acid component with a glass transition temperature of 96°C and ethylene glycol as the diol component PEN (copolymerized PEN3) as the thermoplastic resin B, and examples 4 In the same way, a laminated film is obtained. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use.

(Example 14)

A laminated film was obtained in the same manner as in Example 13 except that the speed of stretching the film in the longitudinal direction after biaxial stretching was 400%/sec. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is excellent.

(Example 15)

In addition to using a glass transition temperature of 90°C, copolymerization is carried out by copolymerizing 50-mol% of 2,6-naphthalene dicarboxylic acid and 50-mol% of isophthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component. Except for the thermoplastic resin B, PEN (copolymerized PEN4) was carried out in the same manner as in Example 4 to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is excellent.

(Example 16)

In addition to using a glass transition temperature of 98°C, 75 mol% of 2,6-naphthalene dicarboxylic acid and 25 mol% of isophthalic acid are used as the dicarboxylic acid The copolymerized PEN (copolymerized PEN5) copolymerized with ethylene glycol as the diol component was used in the same manner as in Example 4 to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is excellent.

(Example 17)

In addition to the use of a glass transition temperature of 103°C, copolymerization of 2,6-naphthalene dicarboxylic acid 80 mol% and isophthalic acid 20 mol% as a dicarboxylic acid component and ethylene glycol as a diol component for copolymerization Except for the thermoplastic resin B, PEN (copolymerized PEN6) was carried out in the same manner as in Example 4 to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is excellent.

(Example 18)

In addition to using a glass transition temperature of 103°C, 70 mol% of 2,6-naphthalene dicarboxylic acid and 30 mol% of 1,8-naphthalene dicarboxylic acid were used as the dicarboxylic acid component, and ethylene glycol was used as the diol component for co-production. The polymerized copolymerized PEN (copolymerized PEN7) was used in the same manner as in Example 4 except for the thermoplastic resin B to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced during the processing of the product, and there is no actual use Questionable. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is excellent.

(Example 19)

In addition to using a glass transition temperature of 103°C, 70 mol% of 2,6-naphthalene dicarboxylic acid and 30 mol% of 2,3-naphthalene dicarboxylic acid were used as the dicarboxylic acid component, and ethylene glycol was used as the diol component for co-production. Except for the thermoplastic resin B, the polymerized copolymerized PEN (copolymerized PEN8) was carried out in the same manner as in Example 4 to obtain a laminated film. The resulting laminated film exhibited the physical properties shown in Table 3 and showed a high Young's coefficient. The laminated film can be continuously produced when processing products, and can be used without problems in actual use. In addition, the extinction ratio showing the polarization characteristics is higher than in Example 4, and the polarization reflection performance is 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 a casting film. The obtained film system showed the physical properties shown in Table 2, and showed a high Young's coefficient in the same manner as in Example 4. On the other hand, since it does not have a layered structure, it does not exhibit specific reflection performance. Furthermore, when compared with the film of Example 1, the film becomes brittle, so the handleability decreases. The film breaks during processing of the product, and the continuous productivity is poor.

(Comparative example 2)

The laminated film was obtained in the same manner as in Example 1 except that the layering device to be used was a device with three slits. The obtained laminated film exhibited the physical properties shown in Table 2, and showed a high Young's coefficient in the longitudinal direction of the film as in Example 1. On the other hand, in response The number of layers is as few as three, and the reflective performance peculiar to the laminated structure is not shown. Furthermore, since the film becomes brittle when compared with the film of Example 1, the handleability is slightly lowered. The laminated film produced film breakage during the processing of the product, and the continuous productivity was poor.

(Comparative example 3)

The cast film obtained in the same manner as in Example 4 was heated by a roller group set at a temperature of 120° C., and then stretched 4.5 times in the longitudinal direction of the film at a temperature set at 135° C., and then temporarily cooled.

By guiding the uniaxially stretched film obtained as described above to a tenter, after preheating with hot air at a temperature of 135°C, the film is stretched 4.5 times at a temperature of 150°C in the width direction of the film, and continuously heated to 220 Transported in an oven at ℃, heat treatment. By trimming both ends of the obtained biaxially stretched film, the laminated film as the target was made into a film roll with a film width of 1500 mm and a length of 200 m.

The obtained laminated film showed the physical properties shown in Table 2, and the Young's coefficient was lower than in Example 4. The laminated film produced film breakage during the processing of the product, and the continuous productivity was poor.

(Comparative example 4)

The cast film obtained in the same manner as in Example 4 was led to a tenter, preheated with hot air at a temperature of 135°C, and then stretched 5.0 times in the width direction of the film at a temperature of 150°C. End trimming, in the form of a roll with a film width of 2000mm, to obtain a laminated film 200m as the target.

The resulting laminated film exhibited the physical properties shown in Table 2. Compared with Example 4, the Young's coefficient decreased, which was the width of the film roll. The film with the alignment axis in the direction, so the strength of the film roll in the winding axis direction is extremely weak. The laminated film produced film breakage during the processing of the product, and the continuous productivity was poor.

(Comparative example 5)

By heating the cast film obtained in the same manner as in Example 4 with a roller group set to a temperature of 120°C, the roller was set to a temperature of 135°C in the longitudinal direction of the film and stretched 4.0 times to carry out repairs. A film roll including a laminated film with a film width of 500 mm and a length of 200 m as a target was obtained.

The obtained laminated film showed the physical properties shown in Table 2, and the Young's coefficient was lower than in Example 4. Furthermore, with the alignment of the thermoplastic resin B generated during stretching, the reflection performance is also greatly reduced compared to the embodiment. The laminated film produced film breakage during the processing of the product, and the continuous productivity was poor.

Claims (13)

A laminated film, characterized in that it is a laminated film formed by alternately laminating a total of 11 or more layers including a layer A of crystalline polyester and a layer B of a thermoplastic resin different from the crystalline polyester. The Young's coefficient in the direction of the alignment axis is 6 GPa or more, and the ratio of the Young's coefficient in the direction of the alignment axis and the direction orthogonal to the same plane is 2 or more. As in the laminated film of claim 1, in a polarized Raman spectrum with a beam diameter of 1 μm and a wavelength of 1390 cm ^-1 , the peak intensity I max in the direction in which the reflectance becomes maximum and the peak intensity I min in the direction orthogonal thereto The ratio I max/I min is 5 or more. 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. The laminated film according to claim 1 or 2, wherein the absolute value of the linear expansion coefficient at a temperature of 40°C or more and 50°C or less in any of the alignment axis direction and the direction orthogonal to the alignment axis direction is 10 ppm/℃ the following. The laminated film according to claim 1 or 2, wherein for the polarized light component parallel to the incident plane including the alignment axis direction, the reflectance at an incidence angle of 10° is taken as R1, and for the relative polarized component including the alignment axis direction The polarized light component perpendicular to the incident surface, when the reflectance at an incident angle of 10° is taken as R2, the reflectance at a wavelength of 550 nm satisfies the following formula (2) and formula (3); R2(550)≦40%. . . (2) . R1(550)≧70%. . . (3). The laminated film according to claim 1 or 2, wherein in the first heating curve of differential calorimetry (hereinafter DSC), the laminated film has a melting peak, and the melting peak top temperature is taken as Tm, and is above Tm-110℃ The range below Tm-60°C has an exothermic peak. The laminated film according to claim 1 or 2, wherein the thermal shrinkage stress at a temperature of 100°C in the direction of the alignment axis is 1 MPa or less. The laminated film according to claim 1 or 2, wherein the absolute value of TMA at a temperature of 100°C in the direction of the alignment axis is 0.5% or less. The laminated film according to claim 1 or 2, wherein the melting peak derived from the thermoplastic resin B by differential scanning calorimetry (DSC) is 5 J/g or less. If the laminated film of claim 1 or 2, wherein the layer A and the layer B satisfy the following conditions;. Layer A: Aromatic polyester containing a dicarboxylic acid component and a diol component as main components, 80-100 mol% of 100 mol% of the dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, and the diol component 80-100mol% of 100mol% is ethylene glycol; Layer B: Aromatic polyester containing dicarboxylic acid component and diol component as main components, 40-75mol% of 100-mol% dicarboxylic acid component is 2,6-naphthalene dicarboxylic acid, 25-60mol% It is a component selected from at least one of the group consisting of isophthalic acid, 1,8-naphthalene dicarboxylic acid and 2,3-naphthalene dicarboxylic acid. The diol component of 100 mol% is 80-100 mol% is ethyl Diol. A film roll formed by winding the laminated film according to claim 1 or 2 along the alignment axis of the laminated film. As in the film roll of claim 11, the width of the laminated film is more than 1000 mm. A method for manufacturing a laminated film, characterized in that it will include a junction A layer of crystalline polyester and a layer B of a thermoplastic resin different from the crystalline polyester are alternately laminated, and a total of 11 or more layers of unstretched film are stretched in the direction of the long side of the film at a rate of 2 to 5 times, and then toward the film The width direction extends 2 to 5 times, and again extends 1.3 to 4 times toward the long side of the film.