JP2017177411A - Laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film that has high mechanical strength even at not only normal temperature but also high temperature while having various functions as a laminate film and can be processed in high yield and with high accuracy in various kinds of processing processes.SOLUTION: The laminate film is composed of eleven layers or more in total formed by alternately laminating an A layer comprising a crystalline polyester and a B layer comprising a thermoplastic resin different from the crystalline polyester. When a Young modulus in an orientation axis direction of the laminate film is a and a Young modulus in a direction perpendicular to the orientation axis direction in the same plane is b, the laminate film satisfies a/b>2 and the laminate film has a peak temperature of loss tangent tanδ of 130°C or more as obtained by performing a dynamic viscoelasticity measurement in the orientation axis direction of the laminate film.SELECTED DRAWING: None

Description

  The present invention relates to a laminated film.

  Thermoplastic resin films, especially biaxially stretched polyester films, have excellent properties such as mechanical properties, electrical properties, dimensional stability, transparency and chemical resistance. It is widely used as a substrate film in the above applications.

  On the other hand, a laminated film in which different resins are alternately laminated is used in the polyester film. In such a laminated film, it is possible to obtain a film having a unique function that cannot be obtained by a single layer film. For example, a film having improved dimensional stability against humidity change and dimensional stability at high temperature ( Patent Document 1), an infrared reflection film that reflects infrared light (see Patent Document 2), and a polarization reflection film (see Patent Document 3) that has polarization reflection characteristics.

JP 2009-279923 A International Publication No. 2013/080987 Special Table 2002-509282

However, since the laminated films described in these patent documents have a structure in which different resins are alternately laminated, mechanical strength and dimensional stability are affected by the influence of the laminated thickness compared to a single-layer film. Tend to decrease. In particular, when a thermosetting resin is coated on the surface of the laminated film, it is necessary to perform a heat treatment at a high temperature in order to cure the resin, so that there is a tendency that mechanical strength and dimensional stability are lowered. For example, when a laminated film is combined with other various films and components to cut out a functional film and cut, or when placed in a high-temperature atmosphere especially in processing such as coating and lamination, the force applied in the film forming direction When a laminated film is deformed or broken, causing problems such as a reduction in processing accuracy and yield during processing, and a decrease in optical properties and quality of the obtained film, or when it is actually mounted on a product. However, there is a problem that a problem with the dimensional change occurs.
Accordingly, the object of the present invention is to solve the above-mentioned problems and to provide various functions as a laminated film, and to have high mechanical strength and dimensional stability not only at room temperature but also at high temperature, and high yield in various processing steps. An object of the present invention is to provide a laminated film that can be processed with a high degree of accuracy and that does not cause problems during actual use.

  The present invention is intended to solve the above-mentioned problem, and the laminated film of the present invention has an alternating layer of layer A made of crystalline polyester and layer B made of a thermoplastic resin different from the crystalline polyester. , When a total of 11 or more layers are laminated and the Young's modulus in the orientation axis direction of the laminate film is a, and the Young's modulus in the direction orthogonal to the orientation axis direction is b And the peak temperature of loss tangent tan δ satisfying a / b> 2 and obtained by performing dynamic viscoelasticity measurement in the orientation axis direction of the laminated film is 130 ° C. or higher. is there.

According to a preferred embodiment of the laminated film of the present invention, the storage elastic modulus at the temperature T in the orientation axis direction and the direction orthogonal to the orientation axis direction of the laminate film is E ′ (orientation axis) (T) and E ′ (non-orientation axis), respectively. When (T), the minimum value in the range of 50 ° C. ≦ T ≦ 150 ° C. of the value Φ (T) defined by the following formula (1) is 0.2 or more.
Φ (T) = [E ′ (orientation axis) (T) −E ′ (non-orientation axis) (T)] / E ′ (orientation axis) (T)
... (1)
According to the preferable aspect of the laminated film of the present invention, the minimum value of E ′ (orientation axis) (T) of the laminated film in the range of 25 ° C. ≦ T ≦ 85 ° C. is 4 GPa or more.

  According to a preferred aspect of the laminated film of the present invention, the carboxylic acid component constituting the crystalline polyester contains naphthalenedicarboxylic acid in an amount of 80 mol% or more.

According to the preferable aspect of the laminated film of the present invention, the reflectance at an incident angle of 10 ° is R1 for a polarized light component parallel to the incident surface including the orientation axis direction of the laminate film, and the orientation axis direction The reflectance at a wavelength of 550 nm satisfies the following formulas (2) and (3), where R2 is the reflectance at an incident angle of 10 ° with respect to a polarized light component perpendicular to the plane of incidence including:
・ R2 (550) ≦ 40% (2)
・ R1 (550) ≧ 70% (3)
According to the preferable aspect of the laminated film of the present invention, only one melting peak of 5 J / g or more is confirmed by differential scanning calorimetry (DSC) of the laminated film.

  According to the present invention, it has high mechanical strength and dimensional stability not only at room temperature but also at high temperature, and is used as a functional film for punching, cutting, especially processing and use in a high temperature atmosphere such as coating and lamination. In particular, a laminated film that can be used suitably and has the effect of being usable without causing problems during mounting can be obtained.

  Since the laminated film of the present invention is a laminated film having a high Young's modulus ratio and a high loss tangent tan δ peak temperature, it is suitable for various optical films and process films.

It is a schematic diagram showing polarized light perpendicular to the incident surface including the film longitudinal direction and polarized light parallel to the incident surface including the film longitudinal direction.

  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 comprises a layer (A layer) made of crystalline polyester (hereinafter sometimes referred to as crystalline polyester A) and a thermoplastic resin different from the crystalline polyester (hereinafter referred to as thermoplastic resin B). A layered film in which a total of 11 or more layers (layer B) are alternately laminated.

  Here, specifically, the crystalline polyester A is subjected to differential scanning calorimetry (hereinafter sometimes referred to as DSC) according to JIS K7122 (1999), and at a temperature rising rate of 20 ° C./min. The resin is heated from 25 ° C. to 300 ° C. (1st RUN), held in that state for 5 minutes, then rapidly cooled to a temperature of 25 ° C. or lower, and again at a rate of temperature increase from 25 ° C. to 20 ° C./min. In the differential scanning calorimetry chart obtained by heating to 300 ° C. (2ndRUN), it refers to a polyester having a crystal melting heat ΔHm determined from the peak area of the melting peak of 15 J / g or more. The crystal melting heat amount of the crystalline polyester A used in the present invention is more preferably 20 J / g or more, and further preferably 25 J / g or more.

  Further, the thermoplastic resin B exhibits optical characteristics or thermal characteristics different from the crystalline polyester A used for the A layer. Specifically, the different optical characteristics means that the refractive index is different by 0.01 or more in any of two orthogonal directions arbitrarily selected in the plane of the laminated film and a direction perpendicular to the plane. Sure. The term “showing different thermal characteristics” means that the DSC shows a melting point or glass transition temperature different from that of the crystalline polyester A.

  In addition, the term “alternately laminated” here means that the A layer and the B layer are laminated in a regular arrangement in the thickness direction. For example, they are stacked in a regular arrangement represented by A (BA) n (n is a natural number). By alternately laminating resins with different optical properties in this way, it is possible to express interference reflection that can reflect the light of the designed wavelength from the relationship between the refractive index difference of each layer and the layer thickness. It becomes.

  In addition, by alternately laminating resins with different thermal properties, it is possible to highly control the orientation state of each layer when manufacturing a biaxially stretched film. Optical properties, mechanical properties, and heat shrinkage properties Can be controlled.

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

  In addition, when the number of layers in which the A layer made of crystalline polyester and the B layer made of a thermoplastic resin different from the crystalline polyester are laminated is less than 11, different thermoplastic resins are laminated. Due to the influence on various physical properties such as film forming properties and mechanical properties, for example, it may be difficult to produce a biaxially stretched film, which may cause problems when combined with other components. .

  On the other hand, in the case of a laminated film in which a total of 11 or more layers are alternately laminated as in the laminated film of the present invention, each thermoplastic resin is uniformly arranged as compared with a laminated film having a number of layers of less than 11 layers. Therefore, it is possible to stabilize the film forming property and mechanical properties. Also, as the number of layers increases, there is a tendency to suppress the growth of orientation in each layer.For example, it becomes easier to control mechanical properties and heat shrinkage properties such as improvement of tear resistance due to interfacial tension. In addition, it is possible to impart a specific optical characteristic that expresses the interference reflection function. The number of layers to be stacked is preferably 100 layers or more, and more preferably 200 layers or more. When 100 or more layers of films are laminated, it is possible to reflect a wide band of light with a high reflectivity, and when 200 or more layers are further laminated, for example, the entire visible light having a wavelength of 400 to 700 nm can be reflected. It becomes almost reflective. In addition, although there is no upper limit to the number of layers to be stacked, as the number of layers increases, it may cause an increase in manufacturing cost due to an increase in size and complexity of the manufacturing apparatus. It becomes.

  In the laminated film of the present invention, when the Young's modulus in the orientation axis direction of the laminated film is a and the Young's modulus in the direction orthogonal to the orientation axis direction is b, a / b (orientation axis direction) Loss tangent tan δ obtained by performing dynamic viscoelasticity measurement in the orientation axis direction of the laminated film and satisfying the ratio of Young's modulus of the film to the Young's modulus in the direction orthogonal to the orientation axis direction)> 2. The peak temperature must be 130 ° C. or higher. Specifically, the Young's modulus here refers to a laminate film that is cut into a rectangular shape having a length of 150 mm and a width of 10 mm, and using a tensile tester (Tensilon UCT-100 manufactured by Orientec) at room temperature of 23 ° C. and relative humidity. It is obtained from a load-strain curve obtained by conducting a tensile test under a 65% atmosphere with an initial tensile chuck distance of 50 mm and a tensile speed of 300 mm / min. The measurement is performed 5 times for each sample, and the average value is evaluated. In addition, the orientation direction of the laminated film here refers to the direction in which the Young's modulus of the film is measured by changing the direction every 10 ° in the film plane and the Young's modulus is maximized. is there. The Young's modulus is an index indicating the force required at the time of initial deformation of the film. By increasing the Young's modulus, a force is applied to the laminated film when it is used as a processing process or functional film such as punching, cutting, coating and laminating. Deformation can also be suppressed, and it becomes easy to suppress processing defects associated with film deformation and performance changes during use.

However, even if it is attempted to increase a / b (the ratio of the Young's modulus in the direction of the orientation axis to the Young's modulus in the direction orthogonal to the orientation axis direction) by simply selecting the resin or the method for producing the film, a × There is a certain limit to b (the product of the Young's modulus in the orientation axis direction and the Young's modulus in the direction orthogonal to the orientation axis direction). This is because the Young's modulus depends on the strength of orientation of the resin constituting the laminated film in the direction in which the Young's modulus is measured, and at the same time, the stronger the orientation of the resin in one direction, the more the same plane as that direction. The orientation of the resin in the direction perpendicular to the inside becomes weak. Therefore, it is impossible to increase the Young's modulus in each of two orthogonal directions at the same time without limitation.
On the other hand, increasing the Young's modulus in the longitudinal direction of the laminated film is effective for stabilizing the processing process in processing processes such as punching, cutting, coating, and laminating, especially in the process of continuous processing using a roll film. It is. Therefore, by increasing a / b (the ratio of the Young's modulus in the orientation axis direction to the Young's modulus in the direction orthogonal to the orientation axis direction) greater than 2, the Young's modulus on the orientation axis side can be further increased. In addition, the Young's modulus in the direction in which the Young's modulus is maximized (the orientation axis direction of the laminated film) can be easily set to 6 GPa or more, and stabilization of the processing process of the laminated film can be realized. More preferably, a / b (ratio of Young's modulus between the orientation direction of the laminated film and the direction orthogonal to the same plane) is 3 or more. In this case, the Young's modulus in the orientation axis direction of the laminated film is 10 GPa or more. It is also easy to do. Increasing the Young's modulus ratio (a / b) is achieved by the film production method in addition to the selection of the resin, as will be described later. The upper limit of a / b is not particularly defined, but is preferably 10 or less from the viewpoint of film formation stability.
In the case of a single layer or several layers, if the ratio of Young's modulus in the direction of the orientation axis of the laminated film is greater than 2, the laminated film tends to become brittle due to the strength of the orientation of the resin. There was also a case where the value decreased.
Therefore, as in the laminated film of the present invention, the Young's modulus can be obtained by alternately laminating a total of 11 or more layers of A layers made of crystalline polyester A and B layers made of thermoplastic resin B different from crystalline polyester A. Even when the ratio is greater than 2, the interfacial tension at the lamination interface and the buffering effect of the B layer made of the thermoplastic resin B make it possible to increase the ratio of Young's modulus without impairing handling properties, and thus An effect of suppressing deformation can be obtained even when a force is applied to the laminated film at the time of use as a processing film or a functional film such as punching, cutting, coating and laminating.
Further, the loss tangent tan δ here is specifically cut out of a laminated film into a strip shape having a length of 50 mm and a width of 10 mm, and a dynamic viscoelasticity measuring device (EXSTAR DMS6100 manufactured by Seiko Instruments Inc.) is used. Used, temperature range from 25 ° C to 220 ° C under the conditions of tensile mode, frequency 1Hz, distance between chucks 20mm, strain amplitude 10.0μm, gain 1.5, initial value of force amplitude 400mN, heating rate 5 ° C / min It was obtained by measuring with. The loss tangent tan δ is an index indicating whether the film is close to an elastic body or a viscous body when the temperature is changed. At the peak temperature of the loss tangent tan δ, the film is closest to the viscous body. Therefore, by increasing the peak temperature of the loss tangent tan δ in the direction of the orientation axis of the film, it is possible to suppress deformation of the film even in a processing step carried out in a high temperature atmosphere of 130 ° C. or higher such as coating and laminating. it can. Preferably, the peak temperature of the loss tangent tan δ is 140 ° C. or higher, more preferably 150 ° C. or higher. Depending on the composition, the thermosetting hard coat needs to be heated in a high temperature atmosphere of 150 ° C. or higher. However, if the peak temperature of tan δ is 150 ° C. or higher, the film coating is also performed in such a hard coat coating process. Deformation can be suppressed and coating can be performed stably.

In the laminated film of the present invention, the storage elastic modulus at the temperature T in the orientation axis direction and the direction orthogonal to the orientation axis direction of the laminate film is E ′ (orientation axis) (T) and E ′ (non-orientation axis) (T), respectively. It is also a preferable aspect that the minimum value in the range of 50 ° C. ≦ T ≦ 150 ° C. of the value Φ (T) defined by the following formula (1) is 0.2 or more.
Φ (T) = [E ′ (orientation axis) (T) −E ′ (non-orientation axis) (T)] / E ′ (orientation axis) (T)
... (1)
Specifically, the storage elastic modulus here refers to a laminated film cut into a strip of 50 mm length × 10 mm width, and using a dynamic viscoelasticity measuring device (EXSTAR DMS6100 manufactured by Seiko Instruments Inc.). , Measured in the temperature range from 25 ° C to 220 ° C under the conditions of tensile mode, frequency 1 Hz, distance between chucks 20 mm, strain amplitude 10.0 μm, gain 1.5, force amplitude initial value 400 mN, and heating rate 5 ° C / min. It is what I asked for. Φ (T) is an index showing the anisotropy of the storage elastic modulus of the film at the temperature T. Even when trying to increase Φ (T) simply by selecting a resin or manufacturing a film, there is a certain limit to E ′ (orientation axis) (T) × E ′ (non-orientation axis) (T). is there. This is because the storage elastic modulus depends on the strength of the orientation of the resin constituting the laminated film in the direction of measuring the storage elastic modulus, and at the same time, the stronger the orientation of the resin in one direction, the more same the direction. This is because the orientation of the resin in the direction orthogonal to each other in the plane becomes weak, and it is impossible to simultaneously increase the storage elastic modulus in each of the two orthogonal directions indefinitely.
On the other hand, it is possible to increase the storage elastic modulus in the longitudinal direction of the laminated film in processing steps in a high temperature atmosphere such as punching and cutting, particularly in a coating and laminating atmosphere, and in a processing step using a roll-shaped film. It is effective for stabilizing the machining process. Therefore, by setting the minimum value of Φ (T) in the range of 50 ° C. ≦ T ≦ 150 ° C. to 0.2 or more, E ′ (orientation axis) (T) can be further increased, and the laminated film is processed. Process stabilization can be realized. The minimum value of Φ (T) in the range of 50 ° C. ≦ T ≦ 150 ° C. is preferably 0.4 or more, more preferably 0.5 or more.

  In the laminated film of the present invention, it is also a preferred aspect that the minimum value of E ′ (orientation axis) (T) of the laminated film in the range of 25 ° C. ≦ T ≦ 85 ° C. is 4 GPa or more. The storage elastic modulus E ′ (orientation axis) (T) is an index indicating the force required to deform in the orientation axis direction when the film temperature is T. Increased storage elastic modulus E '(orientation axis) (T) adds force to the laminated film during punching, cutting, especially in high-temperature processing processes such as coating and laminating, and when used as a functional film. In addition, deformation can be suppressed even when the temperature changes, and it becomes easy to suppress processing defects associated with film deformation and performance changes during use. Preferably, the minimum value in the range of 25 ° C. ≦ T ≦ 85 ° C. of the storage elastic modulus E ′ (orientation axis) (T) in the direction in which the Young's modulus is maximum (orientation axis direction of the laminated film) is 5 GPa or more. More preferably, it is 6 GPa or more.

  Moreover, in the laminated | multilayer film of this invention, it is also a preferable aspect that the Young's modulus in the orientation axis direction of a laminated | multilayer film is 6 GPa or more. The Young's modulus is an index indicating the force required at the time of initial deformation of the film. By increasing the Young's modulus, a force is applied to the laminated film when it is used as a processing process or functional film such as punching, cutting, coating and laminating. Deformation can also be suppressed, and it becomes easy to suppress processing defects associated with film deformation and performance changes during use. Preferably, the Young's modulus in the orientation axis direction of the laminated film is 8 GPa or more, more preferably 10 GPa or more. As the Young's modulus increases, the laminated film becomes difficult to deform.For example, since the control range of processing conditions during processing such as punching, cutting, coating and laminating widens, not only processing defects can be suppressed, but also obtained. It is also useful to enhance the performance of the products that are produced. In order to increase the Young's modulus, as will be described later, it is achieved by a film production method in addition to the selection of the resin.

  In the present invention, the laminated film can be a film roll wound along the orientation axis of the laminated film. As described above, increasing the Young's modulus in the longitudinal direction of the laminated film is effective for stabilizing the processing process in processing processes such as punching, cutting, coating, and laminating, especially in the process of continuous processing using a roll film. By obtaining a film roll wound along the orientation axis of the laminated film, a high-quality product can be easily obtained even when a product is obtained using the laminated film of the present invention.

  In order to obtain such a film roll, it is preferable that the angle formed by the orientation axis direction of the laminated film and the flow direction in the film production process is 10 ° or less. If the angle between the orientation axis direction of the laminated film and the flow direction in the film production process is 10 ° or less, the resulting laminated film is continuously wound up into a roll, thereby punching, cutting, coating and laminating. In the processing step such as, particularly, the step of continuously processing using a roll-shaped film, the orientation axis direction and the flow direction of the processing step are the same, so that the processing step is easily stabilized.

  In the laminated film of the present invention, the A layer made of crystalline polyester A is preferably the outermost layer. In this case, since the crystalline polyester A is the outermost layer, a biaxially stretched film can be produced in the same manner as a crystalline polyester film such as a polyethylene terephthalate film or a polyethylene naphthalate film. For example, when the thermoplastic resin B made of an amorphous resin is not the crystalline polyester but is the outermost layer, when obtaining a biaxially stretched film in the same manner as the crystalline polyester film, to production equipment such as rolls and clips There are cases where problems such as film formation failure due to adhesion and surface quality deterioration occur.

  As the crystalline polyester A used in the present invention, a polyester obtained by polymerization from a monomer mainly composed of an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and a diol is preferably used.

  Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalene. Dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, 6,6 '-(ethylenedioxy) di-2-naphthoic acid, 6, Examples include 6 '-(trimethylenedioxy) di-2-naphthoic acid and 6,6'-(butylenedioxy) di-2-naphthoic acid. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, and cyclohexanedicarboxylic acid and ester derivatives thereof. These acid components may be used alone or in combination of two or more.

  In particular, as the carboxylic acid component constituting the crystalline polyester A used in the laminated film of the present invention, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferable from the viewpoint of expressing a high refractive index and increasing Young's modulus. Used. Since terephthalic acid and 2,6-naphthalenedicarboxylic acid include an aromatic ring having high symmetry, it is easy to achieve both a high refractive index and a high Young's modulus by orientation and crystallization. In particular, when the carboxylic acid component constituting the crystalline polyester A contains 2,6-naphthalenedicarboxylic acid, a high Young's modulus can be achieved by increasing the volume ratio of the aromatic ring, and it is industrially versatile. Therefore, a low-cost product can be obtained.

  More preferably, 80 mol% or more of 2,6-naphthalenedicarboxylic acid is included among the carboxylic acid components constituting the crystalline polyester. When naphthalenedicarboxylic acid is contained in an amount of 80 mol% or more, orientation crystallization can be easily performed by performing stretching and heat treatment during the production of the laminated film, and it is easy to increase the Young's modulus.

  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, triethylene glycol, polyalkylene glycol, 2,2-bis (4- Hydroxyethoxyphenyl) propane, isosorbate, spiroglycol and the like. Especially, it is a preferable aspect that ethylene glycol is a main component from a viewpoint that superposition | polymerization is easy.

  Here, the main component refers to 80 mol% or more of the diol component. More preferably, it is 90 mol% or more. These diol components may be used alone or in combination of two or more. It is also possible to partially copolymerize oxyacids such as hydroxybenzoic acid.

  Examples of the thermoplastic resin B used in the present invention include chain polyolefins such as polyethylene, polypropylene, and poly (4-methylpentene-1); ring-opening metathesis polymerization of norbornenes, addition polymerization, and addition copolymerization with other olefins. Polymers such as alicyclic polyolefins; polyamides such as nylon 6, nylon 11, nylon 12 and nylon 66, aramid, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal , Polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate; polypropylene terephthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-na Polyesters such as tartrate, polylactic acid, polybutyl succinate; polyethersulfone, polyetheretherketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, tetrafluoroethylene resin, trifluoroethylene resin Trifluoroethylene chloride resin, tetrafluoroethylene-6 fluoropropylene copolymer, polyvinylidene fluoride, and the like can be used.

  Among these, from the viewpoint of strength, heat resistance, transparency, and versatility, polyester is preferably used from the viewpoints of adhesiveness and laminateability with the crystalline polyester A used for the A layer. These may be used as a copolymer or a mixture.

  In the laminated film of the present invention, when the thermoplastic resin B is a polyester, the polyester obtained by polymerization from a monomer mainly composed of an aromatic dicarboxylic acid component and / or an aliphatic dicarboxylic acid component and a diol component Is preferably used. Here, as the aromatic dicarboxylic acid component, the aliphatic dicarboxylic acid component, and the diol component, the components listed for the crystalline polyester A are preferably used.

  In the laminated film of the present invention, the thermoplastic resin B is preferably an aromatic polyester mainly comprising an aromatic dicarboxylic acid component and a diol component. Particularly, 40 to 75 mol% of 100 mol% of the dicarboxylic acid component is 2,6-naphthalenedicarboxylic acid, and 25 to 60 mol% is composed of isophthalic acid, 1,8-naphthalenedicarboxylic acid, and 2,3-naphthalenedicarboxylic acid. More preferably, 80 to 100 mol% of 100 mol% of the diol component is ethylene glycol.

  Isophthalic acid, 1,8-naphthalenedicarboxylic acid and 2,3-naphthalenedicarboxylic acid have the effect of bending the molecular chain due to their molecular skeleton. As a result, the crystallinity of thermoplastic tree B and the orientation during stretching It becomes possible to reduce the property. As a result, an increase in the refractive index accompanying the orientation crystallization of the B layer during production of the stretched film can be suppressed, and the difference in refractive index from the A layer made of crystalline polyester A (in the case of polarized light reflection performance, the A layer) It is possible to easily generate a difference in refractive index from the orientation axis. As a result, it is possible to develop higher optical characteristics particularly when the polarization reflection characteristics are developed.

  In order to obtain a laminated film having an interference reflection function, the thermoplastic resin B is preferably an amorphous resin. Compared with crystalline resin, amorphous resin is less likely to be oriented when a biaxially stretched film is produced. Therefore, an increase in refractive index associated with orientation crystallization of B layer made of thermoplastic resin B can be suppressed, It is possible to easily generate a refractive index difference from the A layer made of the conductive polyester A. In particular, this effect becomes remarkable when a heat treatment step is provided when producing a stretched film.

  Of the orientations produced in the stretching process, the orientations produced in the B layer can be completely relaxed in the heat treatment process, and the refractive index difference from the A layer made of crystalline polyester can be maximized.

  The non-crystalline resin here refers to JIS K7122 (1999), which performs differential scanning calorimetry, and heats the resin from 25 ° C. to 300 ° C. (1stRUN) at a temperature rising rate of 20 ° C./min. The differential scanning calorie obtained after holding for 5 minutes in that state and then rapidly cooling to a temperature of 25 ° C. or lower, and again heating from 25 ° C. to 300 ° C. at a heating rate of 20 ° C./min (2ndRUN). In the measurement chart, the amount of heat of crystal melting ΔHm obtained from the peak area of the melting peak is a resin having 5 J / g or less. The amorphous resin used in the present invention is more preferably a resin that does not show a peak corresponding to crystal melting.

  In order to obtain a laminated film having an interference reflection function, as the thermoplastic resin B, a crystalline resin having a melting point 20 ° C. lower than the melting point of the crystalline polyester A is also preferably used. In this case, in the heat treatment step, the heat treatment can be completely relaxed 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 difference in refractive index with the A layer can be maximized. Preferably, the difference in melting point between the crystalline polyester A and the thermoplastic resin B is 40 ° C. or higher. In this case, since the temperature selection range in the heat treatment step is widened, the relaxation of the orientation of the thermoplastic resin B can be promoted and the orientation of the crystalline polyester can be more easily controlled.

  As a preferable combination of the crystalline polyester A and the thermoplastic resin B, the absolute value of the difference between the SP values is preferably 1.0 or less. When the absolute value of the difference in SP value is 1.0 or less, delamination between the A layer and the B layer is difficult to occur. More preferably, the crystalline polyester A and the thermoplastic resin B are made of a combination provided with the same basic skeleton.

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

  In order to obtain a laminated film having an interference 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, since the orientation in the thermoplastic resin B does not proceed when the optimum stretching temperature is taken to stretch the crystalline polyester in the stretching step, the refractive index difference from the A layer made of the crystalline polyester is increased. It can be taken big. More preferably, the glass transition temperature of the thermoplastic resin B is 20 ° C. or more lower than the glass transition temperature of the crystalline polyester A.

  In a production method suitable for obtaining the laminated film of the present invention to be described later, oriented crystallization of the thermoplastic resin B is likely to proceed, and a desired interference reflection function may not be obtained. However, the glass transition of the thermoplastic resin B may occur. By making the temperature 20 ° C. or more lower than the glass transition temperature of the crystalline polyester A, oriented crystallization can be suppressed.

  In addition, various additives such as antioxidants, heat stabilizers, weather stabilizers, ultraviolet absorbers, organic lubricants, pigments, dyes, organic or inorganic fine particles, fillers, charging agents are included in thermoplastic resins. An inhibitor, a nucleating agent, etc. can be added to such an extent that the characteristic is not deteriorated.

  In the laminated film of the present invention, the reflectance at an incident angle of 10 ° for the polarization component parallel to the incident surface including the orientation axis direction of the laminated film is R1, and the incident surface including the orientation axis direction of the laminated film is On the other hand, when the reflectance at an incident angle of 10 ° is R2 for a polarized light component perpendicular to it, the reflectance at a wavelength of 550 nm preferably satisfies the following formulas (2) and (3). By satisfying the following formulas (2) and (3), it becomes possible to impart a polarization reflection characteristic of reflecting either polarized light and transmitting the other polarized light.

In order to obtain a film satisfying the following formula (2), the refractive index difference between the A layer and the B layer in the orientation axis direction of the laminated film is 0.02 or less, more preferably 0.01 or less, and still more preferably. , 0.005 or less can be adjusted by the combination of resins. In addition, in order to obtain a film satisfying the following formula (3), the difference in refractive index between the A layer and the B layer in the direction orthogonal to the orientation axis direction of the laminated film is 0.08 or more, more preferably 0. It can be adjusted by selecting a resin combination of 1 or more, more preferably 0.15 or more, and film forming conditions. Examples of the optimum combination are as described above.
R2 (550) ≦ 40% (2)
R1 (550) ≧ 70% (3).

  Further, in the laminated film of the present invention, differential scanning calorimetry is performed, and the differential scanning calorimetry obtained by heating the laminated film from 25 ° C. to 300 ° C. (1stRUN) at a rate of temperature increase of 20 ° C./min. In the chart, it is also preferable that only one melting peak having a heat of crystal melting ΔHm determined from the peak area of 5 J / g or more is confirmed. The fact that only one melting peak of 5 J / g or more is confirmed by differential scanning calorimetry 1st RUN means that the melting peak is derived from crystalline polyester, so that thermoplastic resin B is oriented and crystallized. Indicates that it is not. Therefore, it becomes easy to increase the difference in refractive index between the layers A and B of the thermoplastic polyester B different from the crystalline polyester and to obtain a laminated film having high optical performance. Is possible.

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

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

  First, crystalline polyester A and thermoplastic resin B are prepared in the form of pellets. The pellets are dried in hot air or under vacuum as necessary, and then supplied to a separate extruder. In the extruder, the resin melted by heating is made uniform in the extrusion amount of the resin by a gear pump or the like, and foreign matter, modified resin, or the like is removed through a filter or the like. These resins are fed into a multilayer laminating apparatus.

  As the multilayer laminating apparatus, a multi-manifold die, a feed block, a static mixer, or the like can be used. However, in order to efficiently obtain the configuration of the present invention, it is preferable to use a feed block having 11 or more fine slits. . By using such a feed block, the apparatus does not become extremely large, so that foreign matter due to thermal deterioration is small, and even when the number of stacks is extremely large, highly accurate stacking is possible. Also, the stacking accuracy in the width direction is significantly improved as compared with the prior art. Moreover, in this apparatus, since the thickness of each layer can be adjusted with the shape (length, width) of a slit, it becomes possible to achieve arbitrary layer thickness.

  And the lamination sheet discharged from die | dye is extruded on cooling bodies, such as a casting drum, and a casting film is obtained by cooling and solidifying. At this time, it is preferable that the discharged sheet is brought into close contact with the cooling body by an electrostatic force using an electrode such as a wire shape, a tape shape, a needle shape, or a knife shape, and is rapidly cooled and solidified. In addition, as a method of bringing the discharged sheet into close contact with the cooling body, a method of blowing air from a slit-like, spot-like or planar device and a method using a nip roll are also preferable modes.

  The casting film thus obtained is preferably biaxially stretched. Here, biaxial stretching refers to stretching the film in the longitudinal direction and the width direction.

  Furthermore, as a suitable biaxial stretching method for obtaining the laminated film of the present invention, the film is stretched at a magnification of 2 to 5 times in the film longitudinal direction, then stretched at 2 to 5 times in the film width direction, and further the film longitudinal direction again. It is necessary to stretch 1.3 to 4 times in the direction. The details are as follows.

  The obtained cast film is first stretched in the longitudinal direction. Stretching in the longitudinal direction is usually performed by the difference in the peripheral speed of the roll. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. Although it changes with kinds of resin as a draw ratio, it is preferred that it is 2 to 5 times. The purpose of the first stretching in the longitudinal direction is to provide the minimum orientation necessary for improving the uniform stretchability in the subsequent stretching in the film width direction. Therefore, when the draw ratio is set to a ratio larger than 5 times, a film having a sufficient draw ratio may not be obtained at the time of film width direction stretching described later and re-stretching in the longitudinal direction performed after the process. Moreover, when the draw ratio is less than 2, the necessary minimum orientation cannot be imparted at the time of stretching, and thickness unevenness may occur in the film longitudinal direction, resulting in a reduction in quality. Further, the stretching temperature is preferably a temperature of glass transition temperature to glass transition temperature + 30 ° C. of crystalline polyester A constituting the laminated film.

  The uniaxially stretched film thus obtained is subjected to surface treatment such as corona treatment, flame treatment and plasma treatment as necessary, and then functions such as slipperiness, easy adhesion and antistatic properties are applied in-line. It can also be given by.

  Subsequently, the uniaxially stretched film is stretched in the width direction. Stretching in the width direction is usually performed by using a tenter and transporting the film while holding both ends of the film with clips. Although it changes with kinds of resin as a magnification of extending, it is usually preferred that it is 2 to 5 times. The purpose of stretching in the width direction is to provide the minimum orientation necessary for imparting high stretchability in the subsequent stretching in the film longitudinal direction. For this reason, when the stretching ratio is set to a ratio larger than 5 times, a film having a sufficient stretching ratio may not be obtained at the time of re-stretching in the longitudinal direction of the film that is performed following this step. Further, when the draw ratio is less than 2, the thickness may be uneven in the film width direction at the time of drawing, and the quality may be lowered. Moreover, it is preferable that extending | stretching temperature is between the glass transition temperature of the crystalline polyester A which comprises a laminated | multilayer film-glass transition temperature +30 degreeC, or between the glass transition temperature-the crystallization temperature of crystalline polyester.

  Subsequently, the obtained biaxially stretched film is stretched again in the longitudinal direction. This stretching in the longitudinal direction is usually performed by the difference in the peripheral speed of the roll. This stretching may be performed in one stage, or may be performed in multiple stages using a plurality of roll pairs. Although the draw ratio varies depending on the type of resin, it is preferably 1.3 to 4 times. The first purpose of the second stretching in the longitudinal direction is to orient the film as strongly as possible in the longitudinal direction of the film, and as a result, the resin is strongly oriented by stretching in the longitudinal direction again. The ratio of the Young's modulus of the laminated film is made larger than 2, the minimum value of Φ (T) of the laminated film in the range of 50 ° C. ≦ T ≦ 150 ° C. is 0.2 or more, and E ′ of the laminated film The minimum value of (orientation axis) (T) in the range of 25 ° C. ≦ T ≦ 85 ° C. can be 4 GPa or more. In particular, the higher the draw ratio in the longitudinal direction, the higher the Young's modulus ratio, the value of Φ (T) can be increased, or the value of E ′ (orientation axis) (T) can be increased. The Young's modulus ratio is set to 3 or more, and the minimum value of Φ (T) in the range of 50 ° C. ≦ T ≦ 150 ° C. is set to 0.5 or more, or E ′ (orientation axis) (T) is 25 ° C. ≦ T ≦ It is easy to set the minimum value in the range of 85 ° C. to 6 GPa or more.

  The second purpose of the second stretching in the longitudinal direction is to increase the peak temperature of the loss tangent tan δ obtained by performing dynamic viscoelasticity measurement on the orientation axis of the laminated film. Although it is possible to set the peak temperature of the loss tangent tan δ to 130 ° C. or higher only by the first stretching in the longitudinal direction, the stretching temperature is also increased in accordance with the target peak temperature to further increase the peak temperature. There is a need. However, if the first stretching in the longitudinal direction is performed at a temperature higher than the glass transition temperature + 30 ° C. of the crystalline polyester A constituting the laminated film, adhesion occurs between the stretching roll and the laminated film, and Stretching unevenness may occur in the film, or the stretching roll may be damaged. Moreover, the peak temperature of the loss tangent tan δ can be set to 130 ° C. or higher by the sequential biaxial stretching that extends in the width direction after the first stretching in the longitudinal direction or the method of stretching only once in the width direction. However, since the stretching speed of the tenter is slow, a sufficient Young's modulus ratio may not be obtained.

  On the other hand, in the second stretching in the longitudinal direction in the biaxial stretching method necessary for obtaining the laminated film of the present invention, the glass transition temperature of the crystalline polyester A constituting the laminated film is higher than 30 ° C. Even if stretching is performed, adhesion between the stretching roll and the laminated film is less likely to occur, so that the stretching temperature can be made higher than the first stretching in the longitudinal direction. As a result, the peak temperature of loss tangent tan δ obtained by performing dynamic viscoelasticity measurement on the orientation axis can be 130 ° C. or higher, preferably 140 ° C. or higher, more preferably 150 ° C. or higher. If the stretching temperature in the second longitudinal direction is too high, orientation of the resin in the longitudinal direction becomes difficult to occur, and a sufficient Young's modulus ratio may not be obtained. Therefore, the stretching temperature in the longitudinal direction for the second time is preferably from the glass transition temperature of the crystalline polyester A constituting the laminated film to the glass transition temperature + 80 ° C., which is necessary for obtaining the laminated film of the present invention. By adopting the axial stretching method, it is possible to achieve both a high Young's modulus ratio and a high loss tangent tan δ peak temperature.

  The laminated film obtained by the production method as described above not only has a high peak temperature of loss tangent tan δ, which is obtained by simply measuring the dynamic modulus of elasticity on the ratio of Young's modulus and the orientation axis. It can also be set as the laminated | multilayer film provided with the polarization | polarized-light reflective characteristic which satisfies 2) and (3). This is because the orientation of the A layer made of crystalline polyester A can be made stronger in the film longitudinal direction during the second stretching in the film longitudinal direction. As a result, the refractive index in the film longitudinal direction and the film This is because a difference occurs in the refractive index in the film width direction perpendicular to the longitudinal direction. Further, as the thermoplastic resin B, by selecting an amorphous resin or a combination of the crystalline polyester A and the thermoplastic resin B having a difference in glass transition temperature and melting point that can relax the orientation in the stretching process and the heat treatment process. Further, the orientation of the thermoplastic resin B can be suppressed, and the polarization reflection property is imparted.

  In addition, the laminated film obtained by the production method as described above can improve surface hardness and dimensional stability by applying a thermosetting hard coat resin in an in-line or off-line process. This not only improves the abrasion resistance, chemical resistance and solvent resistance of the laminated film, but also processes such as punching, cutting and laminating, especially the process of continuously using roll-shaped laminated film. Stabilization can be realized, and a high-quality product can be easily obtained when a product using the laminated film of the present invention is obtained.

(Characteristic measurement method and effect evaluation method)
The characteristic measurement method and effect evaluation method in the present invention are as follows.

(1) Number of layers:
The layer structure of the laminated film was determined by observing a sample cut out using a microtome using a transmission electron microscope (TEM). That is, using a transmission electron microscope H-7100FA type (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 each layer thickness were measured. In some cases, in order to increase the contrast, a staining technique using RuO ₄ or OsO ₄ was used. Also, in accordance with the thickness of the thinnest layer (thin film layer) among all the layers that can be captured in one image, when the thin film layer thickness is less than 50 nm, the thin film layer thickness is 50 nm or more and 500 nm. When it was less than 40,000 times, and when it was 500 nm or more, observation was performed with a magnification of 10,000 times.

(2) Calculation method of layer thickness and number of layers:
The TEM photographic image obtained in the above item (1) was captured at an image size of 720 dpi using a scanner (CanoScan D1230U manufactured by Canon Inc.). Save the image as a bitmap file (BMP) or compressed image file (JPEG) on a personal computer, and then use the image processing software Image-Pro Plus ver.4 (distributor: Planetron Co., Ltd.) The file was opened and image analysis was performed. In the image analysis process, the relationship between the thickness in the thickness direction and the average brightness of the area sandwiched between the two lines in the width direction was read as numerical data in the vertical thick profile mode.

  Using spreadsheet software (Excel 2000), the data of position (nm) and brightness was adopted in sampling step 2 (decimation 2), and then numerical processing of 5-point moving average was performed. Further, the obtained data whose brightness changes periodically is differentiated, and the maximum and minimum values of the differential curve are read by a VBA (Visual Basic for Applications) program. The layer thickness was calculated with the interval between the minimum regions as the layer thickness of one layer. This operation was performed for each photograph, and the layer thickness and the number of layers of all layers were calculated.

(3) Young's modulus:
The laminated film was cut into a strip shape having a length of 150 mm and a width of 10 mm to prepare a sample. Using a tensile tester (Orientec Tensilon UCT-100), an initial tensile chuck distance was set to 50 mm, and a tensile speed was set to 300 mm / min. The measurement was carried out in an atmosphere at room temperature of 23 ° C. and a relative humidity of 65%, and the Young's modulus was obtained from the obtained load-strain curve. The measurement was performed five times for each sample, and the average value was evaluated.
(4) Orientation axis direction of laminated film:
The Young's modulus of the laminated film was measured by changing the direction every 10 ° in the film plane, and the direction in which the Young's modulus was maximized was taken as the orientation axis direction of the laminated film.
(5) Loss tangent tan δ
The laminated film was cut into a strip shape having a length of 50 mm and a width of 10 mm to prepare a sample. Using a dynamic viscoelasticity measuring device (EXSTAR DMS6100 manufactured by Seiko Instruments Inc.), tensile mode, frequency 1 Hz, distance between chucks 20 mm, strain amplitude 10.0 μm, gain 1.5, force amplitude initial value 400 mN, Tan δ was measured in a temperature range from 25 ° C. to 220 ° C. under a temperature rising rate of 5 ° C./min.
(6) The storage elastic modulus laminated film was cut into a strip shape having a length of 50 mm and a width of 10 mm to prepare a sample. Using a dynamic viscoelasticity measuring device (EXSTAR DMS6100 manufactured by Seiko Instruments Inc.), tensile mode, frequency 1 Hz, distance between chucks 20 mm, strain amplitude 10.0 μm, gain 1.5, force amplitude initial value 400 mN, The storage elastic modulus was measured in a temperature range of 25 ° C. to 220 ° C. under a temperature rising rate of 5 ° C./min.
(7) Naphthalenedicarboxylic acid content:
The layer A of the laminated film made of crystalline polyester was dissolved in deuterated hexafluoroisopropanol (HFIP) or a mixed solvent of HFIP and deuterated chloroform, and the composition was analyzed using ¹ H-NMR and ¹³ C-NMR. .

(8) Measurement of reflectance for incident light having a polarization component:
The sample was cut out at 5 cm × 5 cm from the center in the alignment axis direction on the line segment having the maximum length in the alignment axis direction. A basic configuration using an integrating sphere attached to a spectrophotometer (U-4100 Spectrophotometer) manufactured by Hitachi, Ltd., and measurement was performed using an aluminum oxide sub-white plate attached to the apparatus as a reference. The sample was placed behind the integrating sphere with the orientation direction of the laminated film being the vertical direction. In addition, a polarizer made by the attached Grantera Co., Ltd. was installed, and linearly polarized light whose polarization component was polarized at 0 and 90 ° was incident, and the reflectance at a wavelength of 250 to 1500 nm was measured.

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

(9) Crystal heat of fusion ΔHm and glass transition temperature:
The DSC curve of the measurement sample was measured according to JIS-K-7122 (1987) using a differential scanning calorimeter. In the test, the sample was heated from the temperature of 25 ° C. to 300 ° C. at the rate of temperature increase of 20 ° C./min (1stRUN), held in that state for 5 minutes, then rapidly cooled to a temperature of 25 ° C. or lower, and again Heating was performed from 25 ° C. to 300 ° C. at a rate of temperature increase of 20 ° C./min (2ndRUN), and the crystal melting heat amount ΔHm and the glass transition temperature were measured from the differential scanning calorimetry chart obtained at that time. The differential scanning calorimetry chart obtained from 2ndRUN for the resin and 1stRUN for the laminated film was applied. Moreover, the apparatus etc. which were used are as follows.
・ Device: “Robot DSC-RDC220” manufactured by Seiko Denshi Kogyo Co., Ltd.
・ Data analysis "Disk Session SSC / 5200"
Sample mass: 5 mg.

(10) Workability:
A thermosetting hard coat resin was applied to the roll-shaped laminated film, and was heat-treated by being conveyed in an oven heated to 150 ° C. to cure the resin. The state of the laminated film after the heat treatment step was observed, and the following A, B, and C evaluations were performed, and A and B were accepted.
A: The film could be continuously conveyed without deformation or breakage.
B: Although the film was partially deformed or broken, continuous conveyance in the longitudinal direction was possible.
C: The film was completely broken and could not be continuously conveyed in the longitudinal direction.

Example 1
As crystalline polyester A, 2,6-naphthalenedicarboxylic acid is 100 mol% of carboxylic acid components constituting crystalline polyester, neopentyl glycol is 10 mol%, and ethylene glycol is diol component constituting crystalline polyester. 90 mol%, and copolymerized PEN (copolymerized PEN1: melting point 246 ° C., glass transition temperature 112 ° C.) obtained by copolymerizing the above three components was used. Further, as thermoplastic resin B, 2,6-naphthalenedicarboxylic acid is 50 mol% and terephthalic acid is 50 mol% of carboxylic acid components constituting the thermoplastic resin, and neopentyl among diol components constituting the thermoplastic resin. A copolymerized PEN (copolymerized PEN2: no melting point, glass transition temperature of 92 ° C.) in which the glycol was 10 mol% and the ethylene glycol was 90 mol% and the above four components were copolymerized was used.

  The prepared crystalline polyester A and thermoplastic resin B were put into two single-screw extruders, melted at a temperature of 290 ° C., and kneaded. Next, the crystalline polyester A and the thermoplastic resin B are passed through 5 sheets of FSS type leaf disk filters, and then combined with a laminating apparatus having 11 slits while being measured with a gear pump. A laminate in which 11 layers were alternately laminated was obtained. The method of forming a laminate was performed according to the method described in Japanese Unexamined Patent Publication No. 2007-307893 [0053] to [0056].

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

  The obtained cast film was heated with a roll group set at a temperature of 120 ° C., then stretched 3.9 times with a roll set at a temperature of 135 ° C. in the longitudinal direction of the film, and then cooled once. The uniaxially stretched film thus obtained is guided to a tenter, preheated with hot air at a temperature of 115 ° C., and then stretched 3.0 times in the film width direction at a temperature of 135 ° C. to obtain a biaxially stretched film as a film roll. It was. The width of the biaxially stretched film obtained here was 1500 mm.

  Furthermore, after heating the biaxially stretched film with a roll group set at a temperature of 120 ° C., the film is stretched 2.2 times with a roll set at a temperature of 170 ° C. in the longitudinal direction of the film, and both ends of the film are trimmed. The target laminated film was a film roll having a film width of 1000 mm and a length of 200 m.

  The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high loss tangent tan δ peak temperature. Moreover, the interference reflection characteristic derived from the difference in the refractive index of crystalline polyester A and thermoplastic resin B was shown. This laminated film did not deform or break even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even during actual use.

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the laminating apparatus used was an apparatus having 101 slits.

  The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 1. Further, it shows interference reflection characteristics derived from the difference in refractive index between the crystalline polyester A and the thermoplastic resin B. Even when compared with Example 1, it showed high polarization reflection characteristics. This laminated film does not deform or break even when coating thermosetting resin in a high-temperature atmosphere, and can be continuously produced with high accuracy and stability during processing into products. Can be used without problems.

(Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the laminating apparatus used was an apparatus having 201 slits.

  The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 1. In addition, it exhibits interference reflection characteristics derived from the difference in refractive index between the crystalline polyester A and the thermoplastic resin B, and exhibits high polarization reflection characteristics as compared with Example 2, and can be used as a polarization reflection member. It was possible level. This laminated film does not deform or break even when coating thermosetting resin in a high-temperature atmosphere, and can be continuously produced with high accuracy and stability during processing into products. Can be used without problems.

Example 4
A laminated film was obtained in the same manner as in Example 1 except that the laminating apparatus used was an apparatus having 401 slits. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 1. Further, it shows interference reflection characteristics derived from the difference in refractive index between the crystalline polyester A and the thermoplastic resin B, and exhibits high polarization reflection characteristics even compared with Example 3, and is extremely high as a polarization reflection member. It was performance. This laminated film does not deform or break even when coating thermosetting resin in a high-temperature atmosphere, and can be continuously produced with high accuracy and stability during processing into products. Can be used without problems.

(Example 5)
A laminated film was obtained in the same manner as in Example 4 except that the stretching temperature in the second longitudinal direction was 160 ° C. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 4. Further, it shows interference reflection characteristics derived from the difference in refractive index between the crystalline polyester A and the thermoplastic resin B, exhibits high polarization reflection characteristics similar to those of Example 4, and has very high performance as a polarization reflection member. Met. This laminated film was deformed or broken only partially even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even in actual use.

(Example 6)
A laminated film was obtained in the same manner as in Example 4 except that the stretching ratio in the second longitudinal direction was 1.7 times. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 4. Further, it exhibits interference reflection characteristics derived from the difference in refractive index between the crystalline polyester A and the thermoplastic resin B, exhibits the same high polarization reflection characteristics as in Example 3, and can be used as a polarization reflection member. It was of a certain level. This laminated film was deformed or broken only partially even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even in actual use.

(Example 7)
A laminated film was obtained in the same manner as in Example 4 except that the stretching ratio in the second longitudinal direction was 1.5 times. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 4. On the other hand, due to the small difference in refractive index between the crystalline polyester A and the thermoplastic resin B, the polarization reflection performance was similar to that in Example 2. This laminated film was deformed or broken only partially even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even in actual use.

(Example 8)
The cast film obtained in the same manner as in Example 4 was heated with a roll group set at a temperature of 120 ° C., and then stretched 6.0 times with a roll set at a temperature of 125 ° C. in the longitudinal direction of the film. By trimming, a film roll made of a laminated film having a target film width of 500 mm and a length of 200 m was obtained.

  The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high loss tangent tan δ peak temperature. On the other hand, due to the small difference in refractive index between the crystalline polyester A and the thermoplastic resin B, the polarization reflection performance was similar to that in Example 2. This laminated film was deformed or broken only partially even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even in actual use.

Example 9
Polyethylene terephthalate (PET) having a melting point of 256 ° C. and a glass transition temperature of 81 ° C. as the crystalline polyester A, an amorphous resin as the thermoplastic resin B, and cyclohexanedimethanol having a glass transition temperature of 78 ° C. A laminated film was obtained in the same manner as in Example 4 except that copolymerized PET (copolymerized PET) was used. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high loss tangent tan δ peak temperature. This laminated film was deformed or broken only partially even during the coating process of the thermosetting resin in a high temperature atmosphere, and could be used satisfactorily even in actual use.

(Comparative Example 1)
A film was obtained in the same manner as in Example 1 except that a single-layer film of copolymerized PEN1 was used as the cast film. The obtained film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 1. On the other hand, since it does not have a laminated structure, it does not show a specific reflection performance, and the film is more fragile as compared with the film of Example 1, and thus the handleability is lowered. This film was inferior in continuous productivity because the film broke during coating of the thermosetting resin in a high temperature atmosphere.

(Comparative Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the laminating apparatus used was an apparatus having three slits. The obtained laminated film exhibited physical properties as shown in Table 1, and exhibited a high Young's modulus ratio and a high peak loss tangent tan δ temperature as in Example 1. On the other hand, reflecting the fact that the number of layers is as small as three layers, the reflective performance peculiar to the laminated structure is not shown, and the film is more fragile than the film of Example 1, so that the handling property is slightly lowered. . This laminated film was inferior in continuous productivity because the film was broken during the coating process of the thermosetting resin in a high temperature atmosphere.

(Comparative Example 3)
After heating the cast film obtained in the same manner as in Example 4 with a roll group set at a temperature of 120 ° C., the film was stretched 4.5 times with a roll set at a temperature of 135 ° C. in the longitudinal direction of the film, Then it was once cooled.

  The uniaxially stretched film thus obtained is guided to a tenter, preheated with hot air at a temperature of 135 ° C, stretched 4.5 times in the film width direction at a temperature of 150 ° C, and further continuously heated to 220 ° C. Heat treatment was carried out by transporting through the oven. By trimming both ends of the obtained biaxially stretched film, the target laminated film was obtained as a film roll having a film width of 1500 mm and a length of 200 m.

  The obtained laminated film exhibited physical properties as shown in Table 1, and the Young's modulus ratio was lower than that of Example 4. This laminated film was inferior in continuous productivity because the film was broken during the coating process of the thermosetting resin in a high temperature atmosphere.

(Comparative Example 4)
The cast film obtained in the same manner as in Example 4 is guided to a tenter, preheated with hot air at a temperature of 135 ° C., stretched 5.0 times in the film width direction at a temperature of 150 ° C., and both ends of the film are trimmed. As a result, a target laminated film of 200 m was obtained in a roll shape having a film width of 2000 mm.

  The obtained laminated film exhibits physical properties as shown in Table 1, the ratio of Young's modulus is lower than that of Example 4, and has an orientation axis in the width direction of the film roll. Therefore, the strength of the film roll in the winding axis direction was extremely weak. This laminated film was inferior in continuous productivity because the film was broken during the coating process of the thermosetting resin in a high temperature atmosphere.

(Comparative Example 5)
A laminated film was obtained in the same manner as in Example 4 except that the stretching temperature in the second longitudinal direction was 140 ° C. The obtained laminated film exhibited physical properties as shown in Table 1, and the peak temperature of loss tangent tan δ was lower than that of Example 4. This laminated film was inferior in continuous productivity because the film was broken during the coating process of the thermosetting resin in a high temperature atmosphere.

(Comparative Example 6)
A laminated film was obtained in the same manner as in Example 4 except that the stretching temperature in the second longitudinal direction was 150 ° C. The obtained laminated film exhibited physical properties as shown in Table 1, and the peak temperature of loss tangent tan δ was lower than that of Example 4. This laminated film was inferior in continuous productivity because the film was broken during the coating process of the thermosetting resin in a high temperature atmosphere.

1. 1. Film longitudinal direction 2. Polarized light perpendicular to the incident plane including the longitudinal direction of the film Polarized light parallel to the incident plane including the film longitudinal direction

Claims (6)

  A laminated film in which A layers made of crystalline polyester and B layers made of a thermoplastic resin different from the crystalline polyester are alternately laminated in total 11 layers or more, and the Young in the direction of the orientation axis of the laminated film When the rate is a and the Young's modulus in the direction orthogonal to the orientation axis direction is b, a / b> 2 is satisfied, and dynamic viscoelasticity measurement is performed in the orientation axis direction of the laminated film. A laminated film characterized by having a peak temperature of loss tangent tan δ of 130 ° C. or higher. When the storage elastic modulus at the temperature T in the orientation axis direction and the direction perpendicular to the orientation direction of the laminated film is E ′ (orientation axis) (T) and E ′ (non-orientation axis) (T), the following formula (1) 2. The laminated film according to claim 1, wherein a minimum value in a range of 50 ° C. ≦ T ≦ 150 ° C. of the value Φ (T) defined by is 0.2 or more.
Φ (T) = [E ′ (orientation axis) (T) −E ′ (non-orientation axis) (T)] / E ′ (orientation axis) (T) (1)   3. The laminated film according to claim 1, wherein a minimum value of E ′ (orientation axis) (T) in the range of 25 ° C. ≦ T ≦ 85 ° C. is 4 GPa or more.   The laminated film according to any one of claims 1 to 3, wherein the carboxylic acid component constituting the crystalline polyester contains 80 mol% or more of naphthalenedicarboxylic acid. The reflectance at an incident angle of 10 ° for a polarization component parallel to the incident surface including the alignment axis direction is R1, and the polarization component perpendicular to the incident surface including the alignment axis direction is at an incident angle of 10 °. The laminated film according to any one of claims 1 to 4, wherein when the reflectance is R2, the reflectance at a wavelength of 550 nm satisfies the following formulas (2) and (3).
R2 (550) ≦ 40% (2)
R1 (550) ≧ 70% (3)   The laminated film according to any one of claims 1 to 5, wherein only one melting peak of 5 J / g or more is confirmed by differential scanning calorimetry (DSC).

Images