JP5867203B2 - Multilayer laminated film, window member using the same, and laminated glass - Google Patents

Description

  The present invention relates to a multilayer laminated film in which interference color is difficult to be observed when viewed through a polarizer such as polarized sunglasses, and its use.

  A transparent multilayer laminated film formed by laminating two or more kinds of thermoplastic resins in the thickness direction is used for window glass for buildings, vehicles, etc., and has a scattering prevention function (Patent Document 1) and a heat ray reflection function ( Those having Patent Document 2 and Patent Document 3) are used. Here, such a multilayer laminated film is produced by being biaxially stretched, and the stretch ratios in the longitudinal direction and the transverse direction are usually substantially the same. Therefore, the retardation is small.

  Such a film is used by being attached to a windshield or window glass of an automobile using such a function.

  However, although the known multilayer laminated film does not affect the visibility under natural light (non-polarized light), there is a problem that a strong interference color can be seen when viewed through a polarizer such as polarized sunglasses. When driving with polarized sunglasses, the interference color interferes and the driver feels stressed. In addition, interference fringes may appear on the window glass, which may cause discomfort.

  Even when not wearing polarized sunglasses, sunlight may be polarized due to scattering in the air or reflection from an object, and light from a light source such as a fluorescent lamp may be polarized due to reflection from the object. In such a case, an interference color may be seen even with the naked eye, and a stronger interference color will be seen when viewed through polarized sunglasses.

Japanese Patent Laid-Open No. 10-076620 International Publication No. 2005/040868 Pamphlet JP 2005-535938 A

  An object of the present invention is to provide a multilayer laminated film in which interference color is difficult to be observed even when viewed through a polarizer, and a window member and laminated glass using the multilayer laminated film.

  In order to solve the above problems, the present invention has the following configuration.

  That is, a layer made of a thermoplastic resin (A layer) and at least 10 layers made of a thermoplastic resin having different properties from the resin constituting the A layer (B layer) are alternately laminated, and the incident angle A multilayer laminated film having a retardation at a wavelength of 590 nm at 0 ° of 1700 nm or more and an average transmittance of 80% or more in a wavelength range of 400 nm to 800 nm.

  According to the present invention, when a light beam from a light source such as a solar ray or a fluorescent lamp is viewed through a polarizer, a multilayer laminated film in which the visual recognition of a strong interference color is eliminated, and a window member using the multilayer laminated film Can be obtained.

Diagram for explaining the relationship between incident angle and retardation

  The present inventors have found that when the light that has passed through such a multilayer laminated film is viewed through a polarizer such as polarized sunglasses, the problem that a strong interference color can be seen occurs due to the low retardation of the multilayer laminated film. did. This will be described in detail below.

  When the polarized light passes through an optical anisotropic body having a different refractive index depending on the direction, it is divided into two polarized lights whose vibration directions are orthogonal to each other. Since the two polarized light beams have different velocities, a phase difference occurs after passing through the optical anisotropic body. The two polarized lights after passing through the optical anisotropic body are combined when passing through the polarizer. This synthesized light comes to exhibit various colors depending on the phase difference between the two polarized light after passing through the optical anisotropic body, and the color is called an interference color.

  Retardation is the distance that slow speed light lags behind fast speed light in the two polarized light after passing through an optical anisotropic body, and is expressed by equation (1).

R = d (n ₁ −n ₂ ) (1)
Here, R is retardation, d is the thickness of the optical anisotropic body, n ₂ is the refractive index of the slow axis of the optical anisotropic body, and n ₁ is the refractive index of the fast axis of the optical anisotropic body. . Note that (n ₁ −n ₂ ) is also referred to as birefringence.

  The present invention has been achieved as a result of searching for how the interference color in the multilayer laminated film can be eliminated due to the retardation of the film.

  Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not construed as being limited to the embodiments including the following examples, and the object of the present invention can be achieved. Various embodiments within the scope not departing from the gist are naturally included in the scope of the present invention.

In the multilayer laminated film of the present invention, a layer made of a thermoplastic resin (A layer) and at least 10 layers made of a thermoplastic resin having different properties from the resin constituting the A layer (B layer) are alternately laminated. Thus, it is necessary that the retardation at a wavelength of 590 nm at an incident angle of 0 ° is 1700 nm or more, and the average transmittance in a wavelength range of 400 nm to 800 nm is 80% or more.
Examples of the thermoplastic resin that can be used in the present invention include polyolefins such as polyethylene, polypropylene, and poly (4-methylpentene-1). Examples of cycloolefins include ring-opening metathesis polymerization, addition polymerization, and other olefins of norbornenes. Biodegradable polymers such as alicyclic polyolefin, polylactic acid, and polybutyl succinate, polyamides such as nylon 6, nylon 11, nylon 12, and nylon 66, aramid, polymethyl methacrylate, polychlorinated Vinyl, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate, polypropylene terephthalate, Polyester such as reethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polyether sulfone, polyether ether ketone, modified polyphenylene ether, polyphenylene sulfide, polyether imide, polyimide, polyarylate, tetrafluoroethylene resin, Examples thereof include a trifluorinated ethylene resin, a trifluorinated ethylene resin, a tetrafluoroethylene-6 fluoropropylene copolymer, and polyvinylidene fluoride. Among these, from the viewpoint of strength, heat resistance, and transparency, it is particularly preferable to use a polyester, and the polyester is a polymerization from a monomer mainly composed of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol. Polyester obtained by is preferred. Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyl Examples include dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, and the like. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid and ester derivatives thereof. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. These acid components may be used alone or in combination of two or more thereof, and further may be partially copolymerized with oxyacids such as hydroxybenzoic acid.

  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. Of these, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

  Of the above polyesters, polyethylene terephthalate and its polymer, polyethylene naphthalate and its copolymer, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, and polyhexamethylene terephthalate and its copolymer It is preferable to use a polymer, polyhexamethylene naphthalate and a copolymer thereof.

  In the multilayer laminated film of the present invention, at least two kinds of thermoplastic resins are used, and the two kinds of thermoplastic resins have different properties. The property here means that crystallinity / amorphous property, optical property, thermal property, or physical property is different. By laminating thermoplastic resins having different properties, it is possible to give the film a function that cannot be achieved by a single layer film of each thermoplastic resin. The two types of thermoplastic resins preferably contain the same basic skeleton from the viewpoints of interlayer adhesion and a high-precision laminated structure. The basic skeleton here is a repeating unit constituting the resin. For example, when one resin is polyethylene terephthalate, ethylene terephthalate is the basic skeleton. As another example, when one resin is polyethylene, ethylene is a basic skeleton.

  In order to provide the same basic skeleton and different properties, it is desirable to use a copolymer. That is, for example, when one resin is polyethylene terephthalate, the other resin is a resin in which a part of the terephthalic acid residue and / or ethylene glycol residue is replaced with another divalent organic group as the other resin. This is the mode used. The proportion of other components (sometimes referred to as copolymerization amount) is preferably 10% or more because of the need to obtain different properties. On the other hand, since the difference in adhesion between layers and thermal fluidity is small, 90% or less is preferable because of excellent thickness accuracy and thickness uniformity. More preferably, it is 15% or more and 80% or less. It is also desirable that the A layer and the B layer are used by blending or alloying a plurality of types of thermoplastic resins. By blending or alloying a plurality of types of thermoplastic resins, performance that cannot be obtained with one type of thermoplastic resin can be obtained.

  Moreover, since the multilayer laminated film of this invention consists of thermoplastic resins, it can permeate | transmit electromagnetic waves. Therefore, even if the multilayer laminated film of the present invention is laminated on a window glass of a building or an automatic person's window glass, it does not hinder the use of a device utilizing electromagnetic waves such as a mobile phone.

  In the multilayer laminated film of the present invention, a layer (A layer) composed of a thermoplastic resin and at least 10 layers (layer B) composed of a thermoplastic resin having a property different from the resin constituting at least the A layer are alternately laminated. It is necessary to include the structure. By laminating thermoplastic resins having different properties, it is possible to give the film a function that cannot be achieved with only one thermoplastic resin layer. The number of layers may be increased in accordance with a desired function. For example, in the case of providing tear resistance, a range of 10 to 51 layers is preferable, and a range of 15 to 41 layers is more preferable. When giving heat ray reflection performance, it is preferable to laminate 51 layers or more, more preferably 101 layers or more, and still more preferably 201 layers or more. The higher the number of stacks, the higher the heat ray reflectivity can be realized and the reflection bandwidth can be expanded. However, the upper limit is about 10,000 layers from the viewpoint of stacking accuracy and enlargement of the stacking apparatus. In addition, in order to provide heat ray reflection performance, the optical thickness of two adjacent layers is set to ½ of the wavelength to be reflected, and the thermoplastic resin A and the thermoplastic resin constituting the adjacent two layers It is desirable to select and use a resin having a difference in refractive index of B of 0.03 or more.

  The multilayer laminated film of the present invention needs to have a retardation at a wavelength of 590 nm at an incident angle of 0 ° of 1700 nm or more. When the retardation is 1700 nm or more, it is possible to make it difficult to observe the interference color even when viewed through a polarizer. Even when the multilayer laminated film of the present invention is bonded to a window glass of a building or a window glass of an automobile, the interference color cannot be seen, so that a transparent and good field of view can be provided. The preferable value of retardation is 2000 nm or more, More preferably, it is 2500 nm or more, More preferably, it is 3000 nm or more. By increasing the retardation of the multilayer laminated film, the interference color becomes invisible not only with partially polarized light but also with completely linearly polarized light. As a method of increasing the retardation, a thermoplastic resin having birefringence is used for at least one of the thermoplastic resins constituting the A layer or the B layer of the multilayer laminated film of the present invention, and the uniaxial stretching or one of the directions is performed. This can be achieved by performing biaxial stretching with a higher stretching ratio. Here, with respect to the direction of biaxial stretching, a direction in which the stretching ratio is high is referred to as a high-magnification direction, and a direction in which the stretching ratio is low is referred to as a low-magnification direction. When the thermoplastic resin is a resin having a positive birefringence, the molecular chain is oriented in the high magnification direction, so that the refractive index is different between the high magnification direction and the low magnification direction, and the retardation is increased. On the other hand, when the thermoplastic resin is a resin having negative birefringence, since it is oriented in the low magnification direction, the refractive index is different between the high magnification direction and the low magnification direction, and the retardation is increased. In order to further increase the retardation, it is necessary to increase the stretch ratio in the high magnification direction or lower the stretch ratio in the low magnification direction. However, if the draw ratio in the low magnification direction is less than 1.5 times, the mechanical strength in the low magnification direction becomes low. Therefore, the draw ratio in the low magnification direction is preferably at least 1.5 times or more. Further, the retardation can be increased by increasing the heat treatment temperature. When the draw ratio is anisotropic as in the multilayer laminated film of the present invention, anisotropy occurs in the thermal crystallization degree in the thermal crystallization by heat treatment. Therefore, as the heat treatment temperature increases, the birefringence increases, and as a result, the retardation increases. As the heat treatment temperature, the higher the melting point of the thermoplastic resin is -5 ° C. or lower, the better. In this heat treatment step, the retardation can be increased by reducing the value of the width direction relaxation. As another method, it is advantageous to increase the thickness of the layer having a large retardation of the A layer and the B layer, and the thickness of the A layer or B layer made of a resin having a relatively high birefringence is relatively large. In particular, the thickness of the B layer or the A layer having a low birefringence is 1.2 times or more, preferably 2 times, and more preferably 3 times or more. By doing in this way, the retardation of a multilayer laminated film can be enlarged efficiently, suppressing the increase in film thickness.

  The multilayer laminated film of the present invention needs to have an average transmittance of 80% or more in a wavelength range of 400 nm to 800 nm. More preferably, the average transmittance is 85% or more, and even more preferably 88% or more. By transmitting visible light, even if the multilayer laminated film of the present invention is laminated on a window glass of a building or a window glass of an automobile, it is possible to provide a transparent and good field of view. The achievement method is to reduce the refractive index difference between the A layer and the B layer. When the refractive index of the A layer and the B layer is small, since the reflection does not occur at the interface between the A layer and the B layer, the transmittance can be increased. In this case, the difference in refractive index between the A layer and the B layer is preferably 0.02 or less, more preferably 0.01, and more preferably 0.005.

  Even when there is a difference in refractive index between the A layer and the B layer, the number of stacked layers may be reduced, or the layer thickness may be set so as to extinguish the light reflected at the interface between the A layer and the B layer. The layer thickness that extinguishes the light reflected at the interface between the A layer and the B layer is that the optical thickness of each of the adjacent A layer and B layer is ¼ of any wavelength of 800 nm to 1200 nm. . Another method is to use equivalent membrane theory. The layered structure ABABAB ... of the A layer and B layer is regarded as one layer like (ABA) (BAB) ..., and by adjusting the layer thickness, light in the wavelength range of 400 nm to 800 nm can be obtained. Reflection can be prevented.

  The multilayer laminated film of the present invention has an easy adhesion layer, a hard coat layer, an abrasion resistant layer, a scratch prevention layer, an antireflection layer, a color correction layer, an ultraviolet ray absorption layer, a heat ray absorption layer, a printing layer, a gas barrier on the film surface. A functional layer such as a layer or an adhesive layer is preferably formed.

  The multilayer laminated film of the present invention has a ratio Ttd / Tmd of the thermal shrinkage rate Tmd in the longitudinal direction and the thermal shrinkage rate Ttd in the width direction when treated in an atmosphere at 150 ° C. for 30 minutes at 0.8 to 1.2. Preferably there is. More preferably, Ttd / Tmd is 0.9 or more and 1.1 or less. Thus, by reducing the anisotropy of heat shrinkage, wrinkles do not occur even when heating is performed when the multilayer laminated film of the present invention is laminated on a window glass. Tmd and Ttd are each preferably 20% or less, more preferably 10% or less, more preferably 5% or less, respectively, from the viewpoint of workability. The multilayer laminated film of the present invention has different stretching ratios in the longitudinal direction and the width direction in order to increase the retardation, and therefore, Tmd and Ttd of the multilayer laminated film immediately after biaxial stretching are different. Therefore, Ttd / Tmd can be kept within the above range by performing relaxation heat treatment in the direction of higher draw ratio.

  When relaxation heat treatment is performed at a high heat treatment temperature and Ttd / Tmd is set within the range of 0.8 to 1.2, the retardation is lower than that in the case of tension heat treatment without the widthwise relaxation. End up. Therefore, it is preferable to perform the relaxation heat treatment in a temperature range of 130 ° C to 170 ° C, preferably in a temperature range of 140 ° C to 160 ° C. By performing the relaxation heat treatment in the above temperature range, it is possible to suppress a decrease in retardation while adjusting the heat shrinkage rate Tmd in the longitudinal direction when the treatment is performed in an atmosphere of 150 ° C. for 30 minutes. It is also preferable to combine the relaxation heat treatment in the temperature range of 130 ° C. to 170 ° C. and the relaxation heat treatment at a high temperature of 200 ° C. or higher. The rate of relaxation in the width direction of the relaxation heat treatment in the temperature range of 130 ° C. to 170 ° C. is preferably in the range of 1% to 10%.

  The relationship between the incident angle and retardation of the multilayer laminated film of the present invention will be described with reference to FIG. The slow axis in the figure is the direction in which the average refractive index of the A layer and the B layer is highest in the film plane, and the fast axis is the average refractive index of the A layer and the B layer in the film plane. It is the lowest direction. The average refractive index referred to here is obtained by averaging the refractive indexes in the film in-plane direction of the A layer and the B layer by the layer thicknesses of the A layer and the B layer. Retardations when the incident angle is 0 °, the incident angle changes in the direction of 5, and the incident angle changes in the direction of 6 are shown in equations (2) to (4).

Here, R is retardation, d _A and d _B are the sum of the layer thicknesses of the A layer and B layer, n _Aα and n _Bα are the refractive indexes in the slow axis direction of the A layer and B layer, respectively, and n _Aβ and n B _Bβ is the refractive index of the A layer and B layer in the _fast axis direction, θ _A and θ _B are the refractive angles of the A layer and B layer, and n _Aβγ and n _Bβγ are the _fast axis directions of the A layer and B layer, respectively. The refractive index obtained by averaging the refractive index in the thickness direction and the refractive index in the thickness direction at the refraction angle, n _Aαγ and n _Bαγ are the average refractive index in the slow axis direction and the refractive index in the thickness direction of the A layer and the B layer, respectively, at the refraction angle. Refractive index.

In one embodiment of the multilayer laminate film of the present _{invention, n Aα> n Aβ >> n} Aγ, n Bα = n Bβ = n Bγ, it becomes.

In this case, when the incident angle is inclined in the direction of 5 with respect to the retardation with an incident angle of 0 °, the retardation increases with an increase in the incident angle according to the equation (3). On the other hand, when the incident angle is tilted in the direction of 6, the retardation decreases as the incident angle increases from the equation (4). Therefore, even if no interference color is seen in the multilayer laminated film at an incident angle of 0 °, the interference color may be seen when the multilayer laminated film is viewed from the direction of 6. Also, one of the alternative _{embodiment, n Aα> n Aβ >> n} Aγ, n Bα> n Bβ >> n interference colors and view multilayer laminate film from the same direction as the 6 in each case _Bγ is There is a risk of seeing. This is because when the resin having positive birefringence is used as the thermoplastic resin for the multilayer laminated film of the present invention, the refractive index in the thickness direction becomes smaller than the refractive index in the in-plane direction of the film by performing biaxial stretching. Because. Therefore, the multilayer laminated film of the present invention preferably has a retardation of 1700 nm or more at a wavelength of 590 nm over a range of incident angles from 0 ° to 50 °. More preferably, the retardation is 1700 nm or more at a wavelength of 590 nm over a range of incident angles from 0 ° to 60 °, and more preferably, the retardation is at 1700 nm or more at a wavelength of 590 nm over a range of angles of incidence from 0 ° to 80 °. is there. In this way, even if the incident angle is increased, it becomes difficult to see the interference color, so that a wide viewing angle can be obtained. As an achievement method, the retardation value at an incident angle of 0 ° is set to be larger than 1700 nm. If the retardation value at an incident angle of 0 ° is larger than 1700 nm, the incident value increases, and even if the retardation value decreases, the retardation value of 1700 nm or more can be maintained. Another method is to control the refractive index in the thickness direction. When the refractive index in the thickness direction increases, the degree of decrease in retardation can be reduced, and when the refractive index is increased, retardation can be increased as the incident angle increases even when the incident angle is inclined in the direction of 6. One method is to use a combination of a resin having positive birefringence and a negative birefringence resin. Biaxial stretching described above is performed using a resin having a positive birefringence for the A layer and a negative birefringent resin for the B layer. The retardation by the A layer takes a large value at an incident angle of 0 °, but the retardation decreases when the incident angle is inclined in the direction of 6. On the other hand, since the refractive index in the thickness direction of the B layer is higher than the refractive index in the in-plane direction of the film, the retardation increases when the incident angle is inclined in the direction of 6. Since the increase in the retardation of the B layer compensates for the decrease in the retardation of the A layer when the incident angle is tilted in the direction of 6, the overall retardation of the multilayer laminated film of the present invention is as follows. Slightly decreases or increases.

  The multilayer laminated film of the present invention preferably has an average reflectance of 80% or more in a wavelength range of 300 nm in a wavelength range of 800 nm to 1200 nm, more preferably an average reflectance of 85% or more, more preferably The average reflectance is 90% or more. With such a structure, near infrared rays of 800 nm to 1200 nm can be reflected. Therefore, when the multilayer laminated film of the present invention is bonded to a window glass of a building or a window glass of an automobile, the temperature in the room or in the car The rise can be prevented. In order to obtain an average reflectance of 80% or more over a wavelength range of 300 nm, thermoplastic resins having different refractive indexes are used for the A layer and the B layer, and the optical thickness of the A layer is at least 75 nm in the range of 200 nm to 300 nm. The optical thickness of the B layer is designed to be 0.9 to 1.1 times the optical thickness of the adjacent A layer. The number of layers is preferably 51 or more, more preferably 101 or more, and still more preferably 201 or more. The higher the number of layers, the higher the near-infrared reflectivity can be realized and the reflection bandwidth can be expanded. However, the upper limit is about 10,000 layers from the viewpoint of stacking accuracy and increase in the size of the stacking apparatus. It is preferable to use a crystalline thermoplastic resin for the A layer and an amorphous thermoplastic resin for the B layer. By subjecting the multilayer laminated film of the present invention to biaxial stretching and heat treatment, the in-plane refractive index of the A layer is increased, while the B layer is relaxed and the refractive index is decreased. It is possible to increase the refractive index difference of the layers and obtain a high reflectance. In addition, it is preferable to perform heat treatment so that the orientation of the B layer remains slightly because the retardation increases. It is also preferable to mix 5 wt% to 49 wt% of the crystalline resin with the amorphous resin used for the B layer. Since the orientation of the crystalline resin contained in the resin constituting the B layer remains even after the heat treatment, the retardation of the B layer can be increased. Moreover, when the amorphous resin layer of the B layer contains a crystalline resin, it is possible to prevent moisture from entering when heated and pressurized, and to suppress deterioration of the film.

  The multilayer laminated film of the present invention preferably reflects not only a wavelength range of 800 nm to 1200 nm but also a near infrared ray having a wavelength of 1200 nm or more. By expanding the reflection band, more solar energy can be reflected. The achievement method is that the layer ABABABABABAB ... of the A layer and the B layer is regarded as one layer like (ABA) (BAB) (ABA) (BAB) ... and the layer thickness is adjusted. Thus, even if light having a wavelength of 1200 nm or more is reflected, higher-order reflection in the wavelength range of 400 nm to 800 nm can be eliminated. Specifically, the optical thicknesses of the A layer and the B layer are (1A7B1A), (1B7A1B), (1A7B1A), (1B7A1B), and so on (where 7B is 7B, the optical thickness of the B layer is adjacent to the optical thickness of the A layer) 7 in 7A means that the optical thickness of the A layer is 7 times the optical thickness of the adjacent B layer, and the A and B layers represented by 1A and 1B Are equal optical thicknesses).

  A layer having a thickness of 3 μm or more can be preferably provided as a protective layer on both surface layers of the multilayer laminated film of the present invention. The thickness of the protective layer is preferably 5 μm or more, more preferably 10 μm or more. When the protective layer is thin, ripples may occur in the transmittance / reflectance spectrum due to interference between the surface reflected light and the reflected light at the interface between the surface layer and the adjacent layer. If the phase of the incident light is 0 rad, the phase of the surface reflected light is π rad regardless of the wavelength of the light. On the other hand, the phase of the reflected light at the interface between the adjacent layers of the surface layer varies depending on the layer thickness of the surface layer and the wavelength of the light. When the layer thickness of the surface layer is thin, the change in the phase of the reflected light at the interface between the adjacent layers of the surface layer changes gently with respect to the wavelength of the light. Therefore, ripples are generated in the transmittance / reflectance spectrum when the surface reflected light and the reflected light at the interface between the adjacent layers of the surface layer and the surface layer are strengthened or weakened depending on the wavelength of the reflected light. When the layer thickness of the surface layer is thick, the change in the phase of the reflected light at the interface between the adjacent layers of the surface layer changes rapidly with respect to the wavelength of the light. Therefore, ripples are eliminated in the transmittance / reflectance spectrum. Another advantage of increasing the thickness of both surface layers is that each layer has excellent thickness accuracy and thickness uniformity.

  The multilayer laminated film of the present invention preferably has a thickness non-uniformity of 3% or less in the direction perpendicular to the orientation direction. More preferably, it is 2% or less, and more preferably 1% or less. The orientation direction here is the direction of the orientation angle when measured at an incident angle of 0 ° using a phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments Co., Ltd. The vertical direction is a direction orthogonal to the orientation direction in the film plane. Multi-layer laminated films laminated with thermoplastic resins having different properties, when the stretch ratio is low, it is difficult to perform uniform stretching in the stretching direction because it is stretched only in the stretchable portion having a low elastic modulus. Thickness unevenness may occur in the direction. When the thickness unevenness occurs, there arises a problem that the reflection band is changed and it is difficult to process the multilayer laminated film. Even if the draw ratio is low, a method for reducing the thickness unevenness is to increase the elastic modulus even at a low draw ratio, and low temperature drawing, high speed drawing, addition of a crystalline resin or a branched polymer is preferable.

  For example, in one embodiment of the present invention, polyethylene terephthalate (glass transition temperature: 78 ° C.) is formed in layer A and polyethylene terephthalate copolymer in layer B (cyclohexanedimethanol component is 33 mol% based on the total diol). When a 401 layer laminated film using polymerized polyethylene terephthalate (glass transition temperature 80 ° C.) is stretched at a stretching ratio of 2.7 times, the stretching temperature is set to the glass transition temperature of the B layer + 0 ° C. to 2 ° C. Also, the stretching speed is set to 200% / s or more, the crystalline resin is added to the B layer in an amount of 5 wt% to 49 wt%, and the branched polymer is added to at least one of the A layer or the B layer in an amount of 5 wt% to 49 wt%. To do. In the above embodiment, the crystalline resin added to the B layer is preferably polyester, and particularly preferably polyethylene terephthalate, polybutylene terephthalate, or polypropylene terephthalate. Low-temperature stretching, high-speed stretching, and addition of a crystalline resin facilitate orientational crystallization and increase the elastic modulus even at a low stretching ratio. Addition of a branched polymer increases the elastic modulus even at a low draw ratio due to the entanglement effect of molecular chains.

  The multilayer laminated film of the present invention is preferably used for windows and window members. By laminating the multilayer laminated film of the present invention on a window glass, it is possible to provide a scattering prevention function and a heat ray reflection function, and even when a polarizer such as polarized sunglasses is used, it is transparent and has a good field of view. Can be provided.

  The multilayer laminated film of the present invention is formed by laminating the first glass, the first intermediate film, the multilayer laminated film of the present invention, the second intermediate film, and the second glass in the above order. It is preferable to be used as a laminated glass. PVB (polyvinyl butyral) is preferably used as the intermediate film. When the multilayer laminated film of the present invention has a heat ray reflecting function, it is preferable that at least one of the glass, the intermediate film, and the multilayer laminated film of the present invention contains a UV absorber or a heat ray absorbent. Benzotriazole and benzophenone are preferable as the UV absorber, and lanthanum hexaboride, indium tin oxide, antimony tin oxide, and cesium tungsten oxide are preferable as the heat ray absorber.

  In the laminated glass described above, a transparent (visible light) having a retardation of 1000 nm or more in at least one place between the first glass and the first intermediate film and between the second glass and the second intermediate film. It is preferable that a film having a transmittance of 80% or more is further laminated. By adding and laminating a film with a large retardation, the retardation of the entire laminated glass increases, and when a polarizer such as polarized sunglasses is used, it is possible to provide a more transparent and better view with a wide viewing angle. . At this time, it is desirable that the multilayer laminated film of the present invention and the transparent film having the retardation of 1000 nm or more be arranged so that the slow axis or the fast axis overlap.

Hereinafter, it demonstrates using the Example of the multilayer laminated film of this invention. Even when a thermoplastic resin other than the thermoplastic resin specifically exemplified below is used, the multilayer laminated film of the present invention can be obtained in the same manner by referring to the description of the present specification including the following examples. Can do.
[Methods for measuring physical properties and methods for evaluating effects]
The physical property value evaluation method and the effect evaluation method are as follows.

(1) Retardation A phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments was used. A sample was cut out from the central part in the film width direction at 3.5 cm × 3.5 cm, and placed in the apparatus so that the fast axis of the film was at an angle of 0 ° defined by this measuring apparatus. A retardation at a wavelength of 590 nm at an incident angle of 0 ° and a retardation at a wavelength of 590 nm when the incident angle is tilted by 10 °, 20 °, 30 °, 40 °, and 50 ° in the slow axis direction and the fast axis direction, respectively, were measured. . R (0 °) in Table 1 is a retardation at an incident angle of 0 °, and Rmin is an incident angle of 0 °, or the incident angles are 10 °, 20 °, 30 °, 40 in the slow axis direction and the fast axis direction, respectively. This is the minimum value of retardation measured when tilted at 50 °.

(2) Average transmittance, average reflectance A spectrophotometer (U-4100 Spectrophotometer) manufactured by Hitachi, Ltd. is attached with a 12 ° specular reflection accessory device P / N134-0104, and a wavelength of 250 to 2600 nm at an incident angle φ = 12 degrees. The absolute transmittance and reflectance were measured. Measurement conditions: slit is 2 nm (visible) / automatic control (infrared), gain is set to 2, and scanning speed is 600 nm / min. It was. A sample was cut out from the center in the film width direction at 5 cm × 5 cm and measured. From these results, visible light transmittance and infrared reflectance were determined.

Average transmittance: Average transmittance in the wavelength range of 400 nm to 800 nm
Average reflectance: The average reflectance in the range of 300 nm selected so that the average reflectance is highest in the wavelength range of 800 nm to 1200 nm.

Reflection wavelength 1: the lowest wavelength in the wavelength range for which the average reflectance was obtained Reflection wavelength 2: the highest wavelength in the wavelength range for which the average reflectance was obtained (3) Ttd / Tmd
Samples were cut from the center in the film width direction into 150 mm (film width direction) × 10 mm (film longitudinal direction) and 150 mm (film longitudinal direction) × 10 mm (film width direction). This sample piece is left in an atmosphere of 23 ° C. and a relative humidity of 60% for 30 minutes, and in that atmosphere, two marks are made at intervals of about 100 mm in the longitudinal direction of the sample, and a Nikon universal projector (Model V- 16A) was used to measure the interval between the marks, and the value was taken as A. Next, the sample is allowed to stand for 30 minutes in an atmosphere of 150 ° C. in a tension-free state, and then cooled for 1 hour in an atmosphere of 23 ° C. and a relative humidity of 60%. This was measured and designated as B. At this time, after obtaining the thermal shrinkage rate (Ttd) in the film width direction and the thermal shrinkage rate (Tmd) in the film longitudinal direction from the following formula (6), the thermal shrinkage rate (Ttd) in the film width direction and the film longitudinal direction The ratio Ttd / Tmd of the thermal contraction rate (Tmd) of the resin was determined. For each of the film width direction and the longitudinal direction, the number of tests was 3, and the average value was adopted.

Thermal contraction rate (%) = 100 × (A−B) / A (5)
(4) Thickness unevenness A phase difference measuring device (KOBRA-21ADH) manufactured by Oji Scientific Instruments Co., Ltd. was used. A sample was cut out from the center in the film width direction at 3.5 cm × 3.5 cm, and placed in the apparatus so that the fast axis of the film was at an angle of 0 ° defined by this measuring apparatus. The orientation angle was measured to determine the orientation direction. Next, the sample was cut out to 1.2 m (perpendicular to the film orientation direction) × 5 cm (film orientation direction) from the center in the film width direction. Using a film thickness tester KG601A manufactured by Anritsu Corporation, the film thickness was measured by running 1 m at a speed of 3 m / s in the longitudinal direction of the sample. The film thickness was read with a wide-range electronic micrometer K306C manufactured by Anritsu Corporation, and the thickness unevenness was calculated by the following formula.

    Unevenness of thickness (%) = (maximum thickness−minimum thickness) / average thickness × 100 (6)

(5) Interference color inspection Using a Fuji color light box 100V, 8W (manufactured by KK Shinko Co., Ltd.) as a light source, visual inspection was performed by a crossed Nicols method using two 20 cm × 20 cm polarizing plates. The sample was cut out from the central part in the film width direction to 20 cm (film width direction) × 20 cm (film longitudinal direction), and placed so that the polarizing direction of the polarizing plate on the observation surface side coincided with the film width direction. Evaluation is performed on the part viewed from the front with respect to the film surface, and the evaluation criteria are as follows.

◎: Interference color is hardly visible ○: Interference color is very slight, but no problem in use ×: Strong interference color is visible (Example 1)
Polyethylene terephthalate with IV = 0.65 is used as the thermoplastic resin constituting the A layer (hereinafter also referred to as thermoplastic resin A), and as the thermoplastic resin (hereinafter also referred to as thermoplastic resin B) constituting the B layer. A copolymer of polyethylene terephthalate (polyethylene terephthalate obtained by copolymerizing 33 mol% of cyclohexanedimethanol component with respect to the total diol) was used. The thermoplastic resin A and the thermoplastic resin B are each melted at 280 ° C. by an extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio is thermoplastic resin A / thermoplastic resin by a gear pump. While measuring so that B = 1 / 1.07, it is merged in an 11-layer feed block, and 11 layers are laminated alternately in the thickness direction (A layer is 6 layers, B layer is 5 layers) It was. Next, after supplying to a T-die and forming into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. This unstretched film was longitudinally stretched at 90 ° C., a stretching ratio of 3.3 times, a stretching speed of 100% / s, and led to a tenter that grips both ends with clips, and then stretched at 110 ° C. and 4.2 times horizontally. Heat treatment was performed at 230 ° C., and relaxation in the width direction of about 2% was performed to obtain a multilayer laminated film having a thickness of 80 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 2)
A multilayer laminated film was obtained under the same conditions as in Example 1 except that the longitudinal draw ratio was 3.1 times. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 3)
A multilayer laminated film was obtained under the same conditions as in Example 1 except that the longitudinal draw ratio was 2.7 times. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

Example 4
A multilayer laminated film was obtained under the same conditions as in Example 1 except that the longitudinal draw ratio was 2.3 times. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 5)
A multilayer laminated film was obtained under the same conditions as in Example 1 except that the number of laminated layers was 31 (A layer was 16 layers and B layer was 15 layers). The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 6)
A multilayer laminated film was obtained under the same conditions as in Example 1 except that about 5% in the width direction was relaxed. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 7)
As the thermoplastic resin B, polystyrene (GPPS HF77, PS Japan Co., Ltd.) is used, the number of layers is 31 layers (A layer is 16 layers, B layer is 15 layers), the longitudinal draw ratio is 2.3 times, 150 ° C. A multilayer laminated film was obtained under the same conditions as in Example 1 except that heat treatment was performed and relaxation was performed in the width direction by about 5%. The obtained multilayer laminated film was such that the interference color was hardly visible not only in front but also in the whole film. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 8)
Polyethylene terephthalate having IV = 0.65 was used as the thermoplastic resin A, and Durastar DS2010 (manufactured by Eastman Chemical Co.) was used as the thermoplastic resin B. Thermoplastic resins A and B are melted at 280 ° C. in respective extruders, passed through five FSS type leaf disk filters, and the discharge ratio is thermoplastic resin A / thermoplastic resin B = 1 by a gear pump. / Measured to be 1.07, merged in a 251 layer feed block and laminated 251 layers alternately in the thickness direction (126 layers for layer A and 125 layers for layer B), layer A and layer B The layer thickness of was laminated so that the optical thickness continuously changed from 200 nm to 300 nm from the surface layer toward the opposite surface layer. Next, after supplying to a T-die and forming into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. This unstretched film was longitudinally stretched at 90 ° C., a stretching ratio of 2.7 times, a stretching speed of 100% / s, and led to a tenter that grips both ends with clips, then 110 ° C. and 4.2 times transversely stretched. Heat treatment was performed at 230 ° C., and relaxation in the width direction of about 5% was performed to obtain a multilayer laminated film having a thickness of 56 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

Example 9
As the thermoplastic resin B, a polyethylene terephthalate copolymer (polyethylene terephthalate copolymerized with 33 mol% of cyclohexanedimethanol component with respect to all diols) was used, and the number of layers was 401 layers (A layer was 201 layers and B layer was 200 layers). ), A multilayer laminated film was obtained under the same conditions as in Example 8 except that the film thickness was 90 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 10)
A multilayer laminated film was obtained under the same conditions as in Example 8 except that the number of laminated layers was 601 (A layer was 301, B layer was 300) and the film thickness was 130 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 11)
A multilayer laminated film was obtained under the same conditions as in Example 9 except that the longitudinal stretching temperature was 80 ° C. and the longitudinal stretching speed was 200% / s. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 12)
As the B layer, a polyethylene terephthalate copolymer (polyethylene terephthalate obtained by copolymerizing 33 mol% of cyclohexanedimethanol component with respect to all diols) was compounded with 20 wt% polybutylene terephthalate (Torcon 1100S manufactured by Toray Industries, Inc.). A multilayer laminated film was obtained under the same conditions as in Example 11 except that. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 13)
Polyethylene terephthalate having IV = 0.65 was used as the thermoplastic resin A, and polystyrene (GPPS HF77, PS Japan Co., Ltd.) was used as the thermoplastic resin B. Thermoplastic resins A and B are melted at 280 ° C. in respective extruders, passed through five FSS type leaf disk filters, and the discharge ratio is thermoplastic resin A / thermoplastic resin B = 1 by a gear pump. Measured to be 1.07, merged in a 401 layer feed block, and alternately laminated 401 layers in the thickness direction (A layer is 201 layers, B layer is 200 layers), A layer and B layer The layer thickness of was laminated so that the optical thickness continuously changed from 200 nm to 300 nm from the surface layer toward the opposite surface layer. Next, after supplying to a T-die and forming into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. This unstretched film was longitudinally stretched at 80 ° C., a stretching ratio of 2.3 times, and a stretching speed of 300% / s, led to a tenter that grips both ends with clips, 110 ° C. and 4.2 times transversely stretched, Heat treatment was performed at 150 ° C., and relaxation in the width direction of about 5% was performed to obtain a multilayer laminated film having a thickness of 90 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Example 14)
A multilayer laminated film was obtained under the same conditions as in Example 9 except that the thickness of the outermost layer A was 20 μm and the film thickness was 130 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Comparative Example 1)
Polyethylene terephthalate having IV = 0.65 was used as the thermoplastic resin A, and a polyethylene terephthalate copolymer (polyethylene terephthalate copolymerized with 33 mol% of cyclohexanedimethanol component) was used as the thermoplastic resin B. Thermoplastic resins A and B are melted at 280 ° C. in respective extruders, passed through five FSS type leaf disk filters, and the discharge ratio is thermoplastic resin A / thermoplastic resin B = 1 by a gear pump. While being measured so as to be /1.07, they were merged in an 11-layer feed block to form a laminate in which 11 layers were alternately laminated in the thickness direction (6 layers for A and 5 layers for B). Next, after supplying to a T-die and forming into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. This unstretched film was longitudinally stretched at 90 ° C., a stretching ratio of 3.5 times, a stretching speed of 100% / s, and led to a tenter that grips both ends with a clip, and then 110 ° C. and 3.5 times transversely stretched. Heat treatment was performed at 230 ° C., and relaxation in the width direction of about 2% was performed to obtain a multilayer laminated film having a thickness of 80 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

(Comparative Example 2)
Polyethylene terephthalate having IV = 0.65 was used as the thermoplastic resin A, and Durastar DS2010 (manufactured by Eastman Chemical Co.) was used as the thermoplastic resin B. Thermoplastic resins A and B are melted at 280 ° C. in respective extruders, passed through five FSS type leaf disk filters, and the discharge ratio is thermoplastic resin A / thermoplastic resin B = 1 by a gear pump. / Measured to be 1.07, merged in a 251 layer feed block and laminated 251 layers alternately in the thickness direction (126 layers for layer A and 125 layers for layer B), layer A and layer B The layer thickness of was laminated so that the optical thickness continuously changed from 200 nm to 300 nm from the surface layer toward the opposite surface layer. Next, after supplying to a T-die and forming into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. This unstretched film was longitudinally stretched at 90 ° C., a stretching ratio of 3.5 times, a stretching speed of 100% / s, and led to a tenter that grips both ends with a clip, and then 110 ° C. and 3.5 times transversely stretched. Heat treatment was performed at 230 ° C., and relaxation in the width direction of about 2% was performed to obtain a multilayer laminated film having a thickness of 56 μm. The physical property results are summarized in Table 1, and various conditions are summarized in Table 2.

  The present invention relates to a multilayer laminated film and a method for producing the same. Moreover, the multilayer laminated film of the present invention is suitable as a building material / automotive window and window member.

1: multilayer laminated film 2: incident light 3: slow axis 4: fast axis 5: tilt angle of incident light in the fast axis direction 6: tilt angle of incident light in the slow axis direction 7: slow axis Direction 8: Fast axis direction 9: Thickness direction

Claims (8)

A layer made of a thermoplastic resin (A layer) and at least 10 layers made of a thermoplastic resin having different properties from the resin constituting the A layer (B layer) are alternately laminated, and the incident angle is 0 °. A multilayer laminated film having a retardation at a wavelength of 590 nm of 1700 nm or more and an average transmittance of 80% or more in a wavelength range of 400 nm to 800 nm. The ratio Ttd / Tmd of the thermal shrinkage rate Tmd in the longitudinal direction and the thermal shrinkage rate Ttd in the width direction when treated in an atmosphere at 150 ° C for 30 minutes is 0.8 or more and 1.2 or less. 2. The multilayer laminated film according to 1. The multilayer laminated film according to claim 1 or 2, wherein a retardation at a wavelength of 590 nm is 1700 nm or more over a range of incident angles from 0 ° to 50 °. The multilayer laminated film according to any one of claims 1 to 3, wherein an average reflectance is 80% or more over a wavelength range of 300 nm in a wavelength range of 800 nm to 1200 nm. The multilayer laminated film according to any one of claims 1 to 4, wherein thickness unevenness in a direction perpendicular to the orientation direction is 3% or less. The window member which comprised the multilayer laminated film in any one of Claims 1-5. Laminated glass in which the first glass, the first intermediate film, the multilayer laminated film according to any one of claims 1 to 5, the second intermediate film, and the second glass are laminated in this order. . A transparent film having a retardation of 1000 nm or more is further laminated at least anywhere between the first glass and the first intermediate film and between the second glass and the second intermediate film. The laminated glass according to claim 7.

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