Laminate film

Abstract

To provide a laminate that exhibits superior thermal shielding and that can also enhance appearance and design quality.SOLUTION: The laminate comprises a dielectric multilayer film having a colored layer on one side. When an average reflectance at a wavelength of 900-1000 nm is defined as Ra and an average reflectance at a wavelength of 400-700 nm is defined as Rb, Ra is 50% or more and 100% or less, the shortest wavelength in the 700-900 nm region at which an intermediate value between Ra and Rb occurs is 850 nm or more, and when a surface opposite to the colored layer is defined as an X surface, a water contact angle of the X surface is 5° or more and 60° or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film. [Background technology]

[0002] Laminate films are known that selectively reflect light of specific wavelengths by utilizing the optical interference phenomenon that occurs when two or more materials with different optical properties are regularly laminated with layer thicknesses at the wavelength level of the light. Such laminate films can be endowed with various properties by adjusting the refractive index, number of layers, thickness and distribution of each layer of the materials used, and are therefore used in applications such as cold mirrors, half mirrors, laser mirrors, dichroic filters, heat ray reflective films, near-infrared cut filters, monochrome filters, and polarized reflective films.

[0003] Molded articles obtained by laminating such laminated films onto rigid supports under heat and pressure are used as decorative materials such as decorative panels, various home appliances, building materials, automobile-related parts, etc. In particular, in recent years, in response to restrictions on carbon dioxide emissions for environmental protection, heat-cutting glass, which can suppress the inflow of heat from outside in the summer, particularly heat from sunlight, has attracted attention as window glass for vehicles such as automobiles and trains, and for buildings.

[0004] Examples of such heat-ray-cutting glass include glass in which a heat-ray absorbing material is contained in the glass or in an interlayer film used in laminated glass, and the heat rays are blocked by the heat-ray absorbing material (for example, Patent Document 1), glass in which a metal film is formed on the glass surface by sputtering or the like, and heat rays are reflected and blocked (for example, Patent Document 2), and glass in which a laminated film in which polymers with different refractive indices are alternately stacked is inserted between the glass and the interlayer film, and heat rays are reflected and blocked (for example, Patent Document 3).

[0005] However, the heat-cutting glass of Patent Document 1 converts sunlight incident from outside into thermal energy, which radiates the heat into the room, resulting in reduced heat-cutting efficiency. In addition, this method causes the glass temperature to rise partially by absorbing heat rays, which can lead to damage to the glass itself due to the difference in temperature with the outside air temperature. The heat-cutting glass of Patent Document 2 reflects not only heat rays but also visible light, making it prone to coloration. It also blocks electromagnetic waves, which can adversely affect the use of communication devices inside. On the other hand, the laminated film constituting the heat-cutting glass of Patent Document 3 allows for the layer thickness to be controlled to select the wavelength to be reflected, thereby selectively reflecting light in the near-infrared region that contributes to temperature rise, thereby improving heat-cutting performance while maintaining visible light transmittance. Furthermore, because it does not contain components that block radio waves, such as metals, it also maintains good radio wave transmittance.

[0006] Furthermore, when a laminate film such as that shown in Patent Document 3 is obtained by melt extrusion, for reasons of transparency, heat resistance, weather resistance, chemical resistance, strength, and dimensional stability, a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) is used as the main component of one resin layer, and a thermoplastic resin (e.g., copolymer polyester resin) having optical properties different from that of the polyester resin is used as the other resin layer (e.g., Patent Documents 4 to 6). In particular, when polyethylene naphthalate is used as the main component of one resin layer, the difference in refractive index with the copolymer polyester, which has a low refractive index, can be made large, and therefore a laminate film with high reflectance can be obtained. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-17854 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-310407 [Patent Document 3] International Publication No. 2005 / 040868 [Patent Document 4] Japanese Patent Application Laid-Open No. 2005-059332 [Patent Document 5] Japanese Patent Application Laid-Open No. 2004-249587 [Patent Document 6] International Publication No. 2013 / 137288 Summary of the Invention [Problem to be solved by the invention]

[0008] Because such heat-cutting glass is often used in places where it is visible to the public, such as the windowpanes of vehicles and buildings, appearance is also an important factor. However, when the laminated films of Patent Documents 3 to 6 are used in applications with a colored layer (especially a black layer), such as automobile sunroofs or tinted or printed windowpanes, there is a problem in that water droplets that adhere to the glass during rain or cleaning appear colored red or yellow. The mechanism behind this problem is unclear, but it is speculated that near-infrared light, which is normally reflected by light interference, is reflected at a larger viewing angle due to the lens effect of water droplets, resulting in the reflection of light of red wavelengths. In particular, heat-cutting glass for sunroofs is sometimes provided with a colored layer to prevent the temperature inside the vehicle from rising due to sunlight. However, water droplets appear red or yellow due to rain or cleaning, which is undesirable in terms of appearance.

[0009] The present invention aims to solve the above problems and to provide a laminate that has excellent heat-shielding properties and can improve appearance and design. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention has the following configuration: That is, the laminate film of the present invention is a laminate having a colored layer on one side of a dielectric multilayer film, characterized in that, when the average reflectance at wavelengths of 900 to 1000 nm is Ra and the average reflectance at wavelengths of 400 to 700 nm is Rb, Ra is 50% to 100%, the shortest wavelength that is the intermediate value between Ra and Rb in the wavelength range of 700 to 900 nm is 850 nm or longer, and when the surface opposite to the colored layer is designated as the X-plane, the water contact angle of the X-plane is 5° to 60°.

[0011] The laminated film of the present invention can also be formed into the following embodiments, and can also be used to form laminated glass. [1] A laminate having a colored layer on one side of a dielectric multilayer film, wherein Ra is the average reflectance at a wavelength of 900 to 1000 nm, and Rb is the average reflectance at a wavelength of 400 to 700 nm, and the Ra is 50% or more and 100% or less, and the shortest wavelength that is the intermediate value between Ra and Rb in the wavelength range of 700 to 900 nm is 850 nm or more, and when the surface opposite to the colored layer is the X-plane, the water contact angle of the X-plane is 5° or more and 60° or less. [2] The laminate according to [1], wherein the saturation of reflected light when the X surface is irradiated with light is 20 or less. [3] The laminate according to [1] or [2], wherein the difference between the Ra and the Rb is 20% or more and 90% or less. [4] The laminate according to any one of [1] to [3], wherein the dielectric multilayer film is a laminate film containing a thermoplastic resin as a main component. [5] The laminate according to [4], wherein the laminate film has a structure in which at least 51 layers of at least two types of layers each having a different thermoplastic resin as a main component are regularly laminated. [6] The laminate according to any one of [1] to [5], wherein the distance from the X plane to the dielectric multilayer film is 0.001 mm or more and 2.0 mm or less. [7] The laminate according to any one of [1] to [6], which has a maximum reflectance Rd of 0.1% or more and 15% or less at a wavelength of 400 to 830 nm. [8] The laminate according to any one of [1] to [7], wherein a weather-resistant resin layer, the dielectric multilayer film, an adhesive layer, and a colored layer are arranged in this order, and the colored layer is mainly composed of glass or resin. [9] A laminate according to any one of [1] to [8], comprising a support, an intermediate layer 1, the dielectric multilayer film, an intermediate layer 2, and a colored layer arranged in this order, and the colored layer and the support being primarily composed of glass or resin. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a laminate that has excellent heat-shielding properties and can improve appearance and design. DETAILED DESCRIPTION OF THE INVENTION

[0013] The laminate of the present invention is a laminate having a colored layer on one side of a dielectric multilayer film, characterized in that, when the average reflectance at wavelengths of 900 to 1000 nm is Ra and the average reflectance at wavelengths of 400 to 700 nm is Rb, Ra is 50% or more and 100% or less, the shortest wavelength that is the intermediate value between Ra and Rb in the wavelength range of 700 to 900 nm is 850 nm or more, and when the surface opposite to the colored layer is designated as the X-plane, the water contact angle of the X-plane is 5° or more and 60° or less.

[0014] Although the present invention will be described below with reference to embodiments including the following examples, the present invention should not be construed as being limited to the embodiments including the following examples, and various modifications are naturally possible within the scope of achieving the object of the invention and not departing from the gist of the invention. Furthermore, for the purpose of simplifying the explanation, in the case where a laminate film in which at least two or more types of layers each having different thermoplastic resins as the main components are regularly laminated is used as the dielectric multilayer film, some explanations will be given taking as an example an embodiment in which a laminate film in which two different types of thermoplastic resin layers (hereinafter referred to as layers A and B) are regularly laminated as the dielectric multilayer film, but the same should be understood when a laminate film using three or more types of thermoplastic resin layers or two or more different types of metal layers is used as the dielectric multilayer film.

[0015] The dielectric multilayer film in the present invention refers to a laminate in which two or more different types of layers are stacked together, and refers to a multilayer film that has the function of reflecting, transmitting, and absorbing light of a desired wavelength by controlling the thickness of each layer.

[0016] The dielectric multilayer film constituting the laminate of the present invention is preferably a laminate film containing a thermoplastic resin as a main component. The laminate film preferably has a structure in which two or more different types of layers are regularly laminated to form 51 or more layers, and more preferably has a structure in which at least two or more types of layers containing different thermoplastic resins as main components are regularly laminated to form 51 or more layers. Here, the term "main component" refers to a component that accounts for more than 50% by mass but not more than 100% by mass, when the total components constituting the thermoplastic resin layer are taken as 100% by mass. Hereinafter, the term "main component" can be interpreted in the same way.

[0017] "The thermoplastic resin layers are different" refers to a case where, when two thermoplastic resin layers are compared, at least one of the following 1 to 3 applies, and preferably at least the following "2" applies. Note that when three or more types of thermoplastic resin layers are present, for all of them to be different, it is necessary that, when comparing the two thermoplastic resin layers in any combination, at least one of the following 1 to 3 applies (the same applies when there are four or more types of thermoplastic resin layers). Furthermore, when two or more different types of metal layers are used as layers constituting the dielectric multilayer film, the metal layers are considered to be different if the following 1 or 4 applies. 1: The refractive index differs by 0.01 or more in the main alignment direction (the method for specifying the main alignment direction will be described later). 2: Having different melting points or crystallization temperatures (different melting points or crystallization temperatures means that either the melting point or the crystallization temperature determined by the measurement method described below differs by 3°C or more. Note that cases where one thermoplastic resin layer has a melting point and the other thermoplastic resin layer does not have a melting point, or where one thermoplastic resin layer has a crystallization temperature and the other thermoplastic resin layer does not have a crystallization temperature are also considered to have different melting points or crystallization temperatures.). 3: The composition analyzed by nuclear magnetic resonance spectroscopy or gas chromatography-mass spectrometry differs by 5% by mass or more. 4: The composition of metal elements analyzed by ICP atomic emission spectrometry differs by 5 mass% or more.

[0018] In the dielectric multilayer film constituting the laminate of the present invention, "a structure in which at least two or more layers each having different thermoplastic resins as the main components are regularly laminated to form 51 or more layers" refers to a structure in which 51 or more layers of multiple types of thermoplastic resins each having different main components are laminated to form a certain regularity in the thickness direction. Specific examples include, for example, when there are two types of thermoplastic resin layers (layers A and B) each having different main components, structures in which two types of thermoplastic resin layers are alternately laminated to form a structure such as A(BA)n or B(AB)n (where the repeating units are in parentheses and n is a natural number representing the number of repeating units, the same applies hereinafter) in which the two types of thermoplastic resin layers are alternately laminated to form a structure such as A(BA)n or B(AB)n (where the repeating units are in parentheses and n is a natural number representing the number of repeating units).

[0019] Furthermore, specific examples of a dielectric multilayer film that includes three types of thermoplastic resin layers (A layer, B layer, and C layer) with different main components include an (ABCB)nA structure and an (ABC)nA structure, where A layer, B layer, and C layer are represented as A, B, and C, respectively. By regularly stacking different thermoplastic resin layers in this manner, the dielectric multilayer film can reflect light of a wavelength specified by the relationship between the difference in refractive index of each layer and the layer thickness. Hereinafter, unless otherwise specified, such a dielectric multilayer film will be described using an example of a structure in which two layers, A layer and B layer, are alternately stacked.

[0020] Generally, in a dielectric multilayer film having such a layer structure, based on the principle of interference reflection, the more layers that constitute the film, the higher the reflectivity that can be obtained, and the wider the layer thickness distribution, the wider the reflection band. Therefore, from the viewpoint of increasing the reflectivity, the total number of regularly stacked layers is preferably 101 or more, and more preferably 401 or more. For the above reasons, the greater the total number of layers in the dielectric multilayer film, the better. However, from the viewpoint of preventing an increase in the manufacturing cost due to the increase in the size of the manufacturing equipment as the number of layers increases and preventing a deterioration in handleability due to an increase in the thickness of the dielectric multilayer film itself, a practical range is 1001 or less.

[0021] From the viewpoint of use in heat ray reflection applications, it is important that the average reflectance at wavelengths of 900 to 1000 nm, Ra, is 50% or more and 100% or less. Sunlight has an intensity distribution mainly in the visible light region, and as the wavelength increases, this intensity distribution tends to become smaller. However, for use in applications requiring high colorless transparency, such as heat ray-cutting glass, it is necessary to achieve both colorless transparency and high heat ray-cutting performance. In this way, by efficiently reflecting light with wavelengths of 900 to 1000 nm, which is slightly longer than the visible light region, a laminate can be obtained that achieves both transparency and high heat ray-cutting performance.

[0022] From the above viewpoints, the laminate of the present invention preferably has an Ra of 65% or more and 100% or less, and further preferably 80% or more and 100% or less. By adopting such an embodiment, it is possible to impart high heat-shielding properties to the laminate of the present invention.

[0023] To obtain such a laminate, it is effective to increase the difference in in-plane refractive index between two or more thermoplastic resin layers or metal layers having different optical properties in the dielectric multilayer film used in the laminate. For example, when a biaxially stretched film having a configuration in which two types of thermoplastic resin layers are alternately stacked as the dielectric multilayer film is used, the dielectric multilayer film may be formed by alternately stacking layers containing a crystalline thermoplastic resin as the main component and layers containing a thermoplastic resin that can maintain its amorphous nature even when stretched or that can be melted in a heat treatment process (in other words, it is preferable to form a dielectric multilayer film by alternately stacking layers containing a crystalline thermoplastic resin as the main component and layers containing a thermoplastic resin that can maintain its amorphous nature even when stretched or that can be melted in a heat treatment process). It is also effective to set the in-plane stretching ratio (the product of the stretching ratio in the machine direction (the film transport direction, also referred to as the longitudinal direction)) to 9.0 times or more and the stretching ratio in the transverse direction (the direction perpendicular to the transport direction in the film plane, also referred to as the width direction)) to 18.0 times or to increase the number of layers.

[0024] Here, the in-plane refractive index is the average of the refractive index in the main orientation direction and the refractive index in the direction perpendicular to the main orientation direction within the film plane. When the thermoplastic resin layer not positioned on the outermost surface is mainly composed of an amorphous thermoplastic resin, the in-plane refractive index may be determined in any two directions perpendicular to the plane using a sheet obtained by vacuum drying and then pressing the amorphous thermoplastic resin. This is because amorphous resins generally do not have birefringence, and the refractive index in each direction does not change depending on whether or not the resin is stretched.

[0025] The refractive index can be measured using a laser with a wavelength of 632.8 nm, and a measuring device such as the "SPA-4000" manufactured by SAIRON TECHNOLOGY, INC. can be used. The main orientation direction is the direction with the greatest degree of molecular orientation, and the degree of molecular orientation can be measured using, for example, a molecular orientation analyzer MOA-2001 manufactured by KS Systems Co., Ltd. (now Oji Scientific Instruments Co., Ltd.). When the dielectric multilayer film is a biaxially stretched film, the direction with the greatest stretch ratio is usually the main orientation direction. When the dielectric multilayer film is made of an amorphous resin or a metal film and there is no molecular orientation, the degree of orientation will be approximately the same regardless of the angle, so there is no need to specify the main orientation direction. However, even in this case, the direction with the greatest degree of orientation measured by the molecular orientation analyzer can be treated as the main orientation direction.

[0026] Here, crystalline refers to a heat of fusion of 5 J / g or more in differential scanning calorimetry (DSC). Similarly, amorphous refers to a heat of fusion of less than 5 J / g. Crystalline thermoplastic resins can be oriented and crystallized during the stretching and heat treatment processes to achieve a higher in-plane refractive index than their amorphous state before stretching. Meanwhile, in the case of amorphous thermoplastic resins, heat treatment at a temperature far above the glass transition temperature during the heat treatment process can significantly alleviate any slight orientation that occurs during the stretching process, thereby maintaining the low refractive index of the amorphous state. This layer structure allows for easy creation of a refractive index difference between the crystalline thermoplastic resin and the amorphous thermoplastic resin during the stretching and heat treatment processes in the manufacture of dielectric multilayer films.

[0027] When the dielectric multilayer film is formed as a laminate film having a structure in which two types of layers each having a thermoplastic resin with a different crystallinity as the main component are alternately laminated, it is preferable that the outermost layers on both sides be layers with a relatively high crystallinity (layers having a crystalline thermoplastic resin as the main component) from the viewpoint of suppressing adhesion to rolls, etc., during film formation. A laminate film having such a structure will be described below, and unless otherwise specified, the layer with a relatively high crystallinity will be referred to as Layer A and the layer with a low crystallinity will be referred to as Layer B.

[0028] In such a laminated film, it is preferable that the optical thicknesses of the adjacent A layer and B layer simultaneously satisfy the following formulas (1) and (2). Equation (1): λ / m=2(n α d α cosθa+n β d β cosθb) Formula (2): n α d α =n β d β .

[0029] where λ is the reflected wavelength, n α is the in-plane refractive index of layer A, d α is the thickness of layer A, θa is the angle of light incident on layer A (incident angle), n β is the in-plane refractive index of layer B, d β is the thickness of Layer B, θb is the angle of refraction (refractive angle) of light at Layer B, and m is the order, a natural number. By simultaneously satisfying both Equation (1) and Equation (2), the laminate film can eliminate even-order reflections. This allows for a high average reflectance in the 900-1000 nm wavelength range while a low average reflectance in the visible light range of 400-830 nm. This facilitates achieving a maximum reflectance Rd of 0.1% to 15% in the 400-830 nm wavelength range. As a result, a laminate film with excellent transparency and heat-blocking properties can be obtained. The layer structure and number of layers of such a laminate film can be determined by observing a cross section perpendicular to the film surface (thickness direction) with a transmission electron microscope (TEM), and the thickness of each layer can be measured using the TEM's length measurement function (details will be described later).

[0030] Generally, after a thermoplastic resin is formed into a sheet and stretched, the in-plane refractive index of the laminate film surface is approximately 1.4 to approximately 1.9. Therefore, by adjusting the thickness ratio of adjacent layers A and B (layer A thickness / layer B thickness) to 0.7 or more and 1.4 or less, a laminate film with suppressed even-order reflection can be obtained. Therefore, from the above perspective, the thickness ratio of adjacent layers A and B (layer A thickness / layer B thickness) is preferably adjusted to 0.7 or more and 1.4 or less, and more preferably 0.8 or more and 1.2 or less. By adjusting the thicknesses of adjacent layers A and B to within this range, it becomes easy to maintain the maximum reflectance Rd at wavelengths of 400 to 830 nm (described below) at 15% or less. As a result, reflection in the visible light region of the dielectric multilayer film can be suppressed, reducing coloring and glare.

[0031] It is important that the laminate of the present invention has a shortest wavelength that is the intermediate value between Ra and Rb, where Ra is the average reflectance in the wavelength range of 900 to 1000 nm and Rb is the average reflectance in the wavelength range of 400 to 700 nm. As mentioned above, when the laminate is used in an application requiring high colorless transparency, such as heat-blocking glass, it is preferable to achieve both colorless transparency and high heat-shielding properties, so that Ra is required to be high and Rb is required to be low.

[0032] On the other hand, if the shortest wavelength, which is the intermediate value between Ra and Rb, is lower than 850 nm, the reflected wavelength becomes shorter when the laminate is observed obliquely, as shown in formula (1), and light with a yellow to red wavelength of 600 to 800 nm is more likely to be reflected, resulting in a yellow to orange color. Furthermore, when water droplets adhere to the surface of such a laminate, the incident angle shown in formula (1) becomes smaller, further shortening the reflected wavelength, making it easier to reflect light with a yellow to red wavelength of 600 to 800 nm, resulting in a more intense coloration. In other words, by ensuring that the shortest wavelength, which is the intermediate value between Ra and Rb, is 850 nm or longer, the phenomenon of the laminate appearing colored due to the above mechanism can be reduced. Ra, Rb, and other reflectances and transmittances can be measured using a known spectrophotometer; details of the measurement method will be described later.

[0033] The present inventors prepared laminate films with different reflection wavelength bands and water contact angles and thoroughly investigated the relationship between the reflection wavelength bands and the coloring of water droplets. As a result, they found that, from the viewpoint of suppressing the coloring of attached water droplets, the shortest wavelength that is the intermediate value between Ra and Rb is preferably 870 nm or longer, and even more preferably 890 nm or longer. In order to set the shortest wavelength that is the intermediate value between Ra and Rb to 850 nm or longer or within the above-mentioned preferred range, it is effective to adjust the thickness, layer thickness distribution, and in-plane refractive index of Layer A and Layer B so that the reflection wavelength of Formula (1) is 850 nm or longer or within the above-mentioned preferred range.

[0034] For the same reasons as above, the laminate of the present invention preferably has a maximum reflectance Rd of 0.1% or more and 15% or less at wavelengths of 400 to 830 nm. It is difficult to achieve an Rd lower than 0.1% because of reflection at the interface between the materials. On the other hand, by setting Rd to 15% or less, it becomes easy to set the saturation of the reflected light when irradiating the X-face (described later) with light to 20 or less, and it also reduces coloring caused by the shift of reflection at a wavelength around 830 nm to lower wavelengths when water droplets adhere. From the above viewpoints, Rd is more preferably 0.1% or more and 13% or less, and even more preferably 0.1% or more and 11% or less.

[0035] To achieve an Rd of the laminate of 0.1% or more and 15% or less, or within the above-mentioned preferred range, it is effective to use, for example, a laminate film in which two different thermoplastic resin layers (layer A and layer B) are regularly laminated in a dielectric multilayer film, and to adjust the thickness, layer thickness distribution, and in-plane refractive index of layer A and layer B so that the reflection wavelength of formula (1) is 830 nm or more and the reflectance at wavelengths of 400 to 830 nm is low.

[0036] From the viewpoint of achieving both colorless transparency and high heat-shielding properties, the laminate of the present invention preferably has a difference between Ra and Rb of 20% or more and 90% or less. By having a difference between Ra and Rb of 20% or more, both colorless transparency and high heat-shielding properties can be achieved. On the other hand, when taking into account reflection at the interface between air and the laminate, the upper limit of the difference between Ra and Rb is 90%. From the above viewpoint, the difference between Ra and Rb is more preferably 50% or more and 90% or less, and even more preferably 68% or more and 90% or less.

[0037] A method for adjusting the difference between Ra and Rb of the laminate of the present invention to 20% or more and 90% or less, or within the above-mentioned preferred range, is, for example, to use a laminate film in which two different thermoplastic resin layers (layer A and layer B) are regularly laminated in a dielectric multilayer film, and to adjust the number of layers in the regularly laminated portion. More specifically, by increasing the number of layers, the difference between Ra and Rb can be increased, and Ra can be particularly increased. Furthermore, by adjusting the thickness ratio of the aforementioned adjacent layer A to layer B (thickness of layer A / thickness of layer B) to 0.7 or more and 1.4 or less, the difference between Ra and Rb can be increased, and Rb can be particularly reduced.

[0038] When a laminate film having a structure in which layers A and B are alternately laminated is used as the dielectric multilayer film of the present invention, where the main component of layer A is thermoplastic resin A and the main component of layer B is thermoplastic resin B, polyester resin, acrylic resin, polycarbonate resin, etc. can be used as thermoplastic resin A and thermoplastic resin B. Among these, polyester resins are preferably used as thermoplastic resin A and thermoplastic resin B because of their excellent transparency and formability. Furthermore, when the laminate film has a laminate structure further including layer C, and the main component of layer C is thermoplastic resin C, it is preferable that thermoplastic resin C is also a polyester resin. Here, polyester resin refers to a polymer obtained by condensation polymerization of a dicarboxylic acid component and a diol component.

[0039] In the dielectric multilayer film of the present invention, examples of dicarboxylic acid units of the polyester resins used for thermoplastic resin A, thermoplastic resin B, and thermoplastic resin C include structural units such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acids (1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid), 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, adipic acid, sebacic acid, dimer acid, cyclohexanedicarboxylic acid, and ester-forming derivatives thereof.

[0040] Examples of the diol unit of the polyester resin include structural units such as ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, polyalkylene glycol, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, isosorbate, 1,4-cyclohexanedimethanol, spiroglycol, neopentyl glycol, polyethylene glycol, polypropylene glycol, polybutylene glycol, triethylene glycol, tetraethylene glycol, polytetramethylene ether glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, tributylene glycol, tetrabutylene glycol, and ester-forming derivatives thereof.

[0041] Preferred examples of the dicarboxylic acid units constituting the polyester resin include structural units such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, and isophthalic acid. Preferred examples of the diol units include structural units such as ethylene glycol, 1,4-cyclohexanedimethanol, polyalkylene glycol, polyethylene glycol, tetraethylene glycol, and polytetramethylene ether glycol.

[0042] A preferred embodiment of the laminate film used in the dielectric multilayer film in the laminate of the present invention is one in which the in-plane refractive index of at least one surface of the dielectric multilayer film is 1.68 or more and 1.80 or less. Generally, it is preferable for the surface layer to be a layer with relatively high crystallinity, taking into account factors such as ease of film formation. However, by ensuring that the in-plane refractive index of this surface layer is 1.68 or more, the difference in in-plane refractive index between the surface layer and a layer with relatively low crystallinity can be increased. This makes it easy to achieve an average reflectance Ra of 50% or more and 100% or less at wavelengths of 900 to 1000 nm. Meanwhile, by ensuring that the in-plane refractive index of the surface layer is lower than 1.80, deterioration of the adhesion between the two alternating layers is suppressed, thereby reducing clouding of the dielectric multilayer film and delamination at the interface.

[0043] From the above viewpoints, it is preferable that the thermoplastic resin A used in the dielectric multilayer film in the laminate of the present invention is a crystalline polyester resin having naphthalenedicarboxylic acid units as the main structural unit. This configuration increases the reflectance at the surface of Layer A and facilitates achieving a refractive index difference with Layer B, resulting in a laminate film with better reflective performance. Note that "having naphthalenedicarboxylic acid units as the main structural unit" means that naphthalenedicarboxylic acid units account for more than 50 mol% and up to 100 mol% of all dicarboxylic acid structural units in the polyester resin.

[0044] When thermoplastic resin A is a crystalline polyester resin containing naphthalenedicarboxylic acid units as its main structural units, examples of the naphthalenedicarboxylic acid structural units include 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,3-naphthalenedicarboxylic acid, with 2,6-naphthalenedicarboxylic acid being particularly preferred. Furthermore, when thermoplastic resin B is an amorphous thermoplastic resin, the more naphthalenedicarboxylic acid units there are in thermoplastic resin A, the easier it is to increase the refractive index difference between layer A and layer B.

[0045] From the above viewpoint, when thermoplastic resin A is a crystalline polyester resin having naphthalenedicarboxylic acid units as the main structural unit, the naphthalenedicarboxylic acid units more preferably account for 80 mol% to 100 mol%, and even more preferably 95 mol% to 100 mol% of the dicarboxylic acid units in thermoplastic resin A. From the same viewpoint, the content of thermoplastic resin A in layer A is preferably 80 mol% to 100 mol%, and more preferably 95 mol% to 100 mol%, when the entire layer is taken as 100% by mass.

[0046] In such a laminate film, the difference in in-plane refractive index between Layer A and Layer B is preferably 0.05 or more, more preferably 0.12 or more, and even more preferably 0.14 to 0.35. When the difference in average in-plane refractive index is 0.05 or more, it becomes easy to achieve an average reflectance Ra of 50% to 100% in the wavelength range of 900 to 1000 nm. One example of how to achieve this is to use a crystalline polyester resin as the main component of Layer A and an amorphous thermoplastic resin as the main component of Layer B. In this case, the refractive index difference can be easily achieved during the stretching and heat treatment steps in the production of the laminate film.

[0047] From the viewpoint of increasing reflectance, it is preferable that the difference in the in-plane refractive index between Layer A and Layer B is large, but to increase the difference in the in-plane refractive index requires that the chemical structures of the thermoplastic resins that are the main components of both layers be significantly different, which would deteriorate interlayer adhesion. In light of this, by keeping the difference in the average in-plane refractive index between Layer A and Layer B to 0.35 or less, lamination becomes easier and the heat resistance and handleability of the resulting laminated film are improved.

[0048] In the dielectric multilayer film constituting the laminate of the present invention, metal layers may be used as layers A and B. A dielectric multilayer film having a metal layer may have a multilayer structure in which metal layers and metal oxide layers are alternately stacked. Examples of materials constituting the metal layer include metals such as gold (Au), silver (Ag), copper (Cu), and aluminum (Al), as well as alloys made of these metals.

[0049] Among these, Ag or its alloys, which have excellent visible light transmittance and infrared reflectance, are particularly preferred. Using Ag alloys can further reduce defects such as deterioration due to reactions with sulfur and oxygen, and aggregation that occurs during metal layer formation. Ag alloys containing at least one of Au, Cu, platinum (Pt), palladium (Pd), bismuth (Bi), nickel (Ni), magnesium (Mg), neodymium (Nd), ruthenium (Ru), Al, and zinc (Zn) in an amount of more than 0.05% by mass but less than 3.0% by mass are preferred because they facilitate improved visible light transmittance, infrared reflectance, and corrosion resistance. The above elements added to silver are preferably in a total amount of more than 0.05% by mass but less than 3.0% by mass, based on the total alloy weight. Adding more than 0.05% by mass of these elements facilitates the development of corrosion resistance, while adding less than 3.0% by mass facilitates the maintenance of infrared reflectance due to free electrons.

[0050] The other metal layer to be laminated with the above metal layer preferably uses a metal oxide with a higher refractive index. Examples of metal oxides include zinc oxide (ZnO)-based (which may be doped with dopants such as Al, gallium (Ga), boron (B), indium (In), yttrium (Y), scandium (Sc), fluorine (F), vanadium (V), silicon (Si), germanium (Ge), titanium (Ti), zirconium (Zr), and hafnium (Hf)), tin oxide (SnO2)-based (which may be doped with dopants such as F, antimony (Sb), niobium (Nb), and tantalum (Ta), and indium oxide (In2O3)-based. (Doping with tin (Sn), Ge, molybdenum (Mo), F, Ti, Zr, Hf, Nb, Ta, tungsten (W), tellurium (Te), etc. may be used as a dopant.), gallium oxide (Ga2O3)-based (doping with Sn, etc.), zirconium oxide (ZrO2) (which may contain Cu and Al as additives), titanium oxide (TiO2) (which may contain Cu and Al as additives), etc. may be used, and from the above-mentioned viewpoint, it is preferable to use SnO2-based, In2O3-based, and TiO2-based materials.

[0051] Metal layers and metal oxide layers can be formed by vacuum deposition (induction heating type, electron beam heating type), pulsed laser deposition, magnetron sputtering, and other sputtering methods. Metal oxide layers can also be formed by chemical vapor deposition (CVD), metalorganic chemical vapor deposition (MOCVD), and other methods. Furthermore, if the substrate on which the metal layer or metal oxide layer is formed is a long film or film-like material, it can also be formed using roll-to-roll vacuum deposition or sputtering.

[0052] It is important that the laminate of the present invention has a colored layer on one side of the dielectric multilayer film. In the present invention, the colored layer refers to a layer containing 1% by mass or more of the absorbent described below relative to the entire layer. The colored layer may be laminated directly to the dielectric multilayer film, or may be laminated to the dielectric multilayer film via an adhesive layer, a pressure-sensitive adhesive layer, an intermediate layer, a support, a weather-resistant resin layer, or the like. Preferred configurations include a configuration in which the support 1, intermediate layer, dielectric multilayer film, colored layer, and support 2 are arranged in this order, or a configuration in which the support, intermediate layer 1, dielectric multilayer film, intermediate layer 2, and colored layer are arranged in this order. This configuration allows the laminate to be used particularly effectively in automobile sunroofs, etc. Another preferred configuration is a configuration in which the weather-resistant resin layer, dielectric multilayer film, adhesive layer, and colored layer are arranged in this order. This configuration allows the laminate to be used in applications exposed to sunlight without using a configuration such as laminated glass having multiple supports, which is preferable from the standpoints of manufacturing cost and weight reduction. By configuring the laminate in this manner and arranging the dielectric multilayer film so that it is on the outer side (sun side) of the colored layer, light such as sunlight is reflected by the dielectric multilayer film and the light that is not reflected is absorbed by the colored layer, thereby reducing the amount of infrared light absorbed by the colored layer and reducing heat generation and re-radiation by the colored layer.In the above configuration, the supports 1 and 2 and the intermediate layers 1 and 2 may be the same or different.

[0053] The laminate of the present invention preferably has an L* value in transmission of 1 or more and 40 or less. For example, when the laminate is used in an automobile sunroof, black or smoked colors are generally used to suppress glare and temperature rise due to sunlight through the sunroof and to protect privacy inside the vehicle. From the viewpoint of achieving the above-mentioned objectives, the L* value is more preferably 30 or less, and even more preferably 20 or less. On the other hand, an L* value of 1 or more makes it easy to ensure sufficient visibility when viewing the outside from inside the vehicle. Furthermore, in recent years, light-controlling glass has been used as a sunroof, and when the laminate is such light-controlling glass, the L* value when the switch is turned off preferably falls within the above range. The L* value can be measured using a known spectrophotometer, and the detailed measurement method will be described later.

[0054] To achieve an L* value of 1 or more and 40 or less, or within the above-mentioned preferred range, it is effective to adjust the concentration of the absorber contained in the colored layer. Examples of absorbers used in the colored layer include carbon black, titanium black, copper oxide, black pigments, black metals, and metal compounds. These may be used alone or in combination. Examples of absorbers with coloring function include azo pigments, polycyclic pigments, lake pigments, nitro pigments, nitroso pigments, aniline black, alkali blue, phthalocyanine pigments, cyanine pigments, azo dyes, anthraquinone dyes, quinophthalone dyes, methine dyes, condensed polycyclic dyes, reactive dyes, and cationic dyes. Examples of absorbers with infrared absorption function include tungsten compounds, lanthanum compounds, antimony compounds, indium compounds, and tin compounds, with carbon black and tungsten oxide compounds being preferred. These absorbers are preferably contained in the colored layer, but may also be added to materials used as adhesive layers, bonding layers, intermediate layers, or supports, as described below. It is also effective to use a laminated film having a structure in which A layers and B layers are alternately stacked instead of a metal layer, which is easily stained, as the dielectric multilayer film, and to set the thickness ratio of adjacent A layers to B layers (thickness of A layer / thickness of B layer) to 0.7 or more and 1.4 or less.

[0055] Examples of the support for obtaining the laminate of the present invention include resins, metals, glass, ceramics, etc. The support may be flat or curved and may have any shape. Examples of resins used for the support include acrylic resins such as polycarbonate, cyclic polyolefin, polyarylate, polyethylene terephthalate, and polymethyl methacrylate, ABS resin, and triacetyl cellulose, which may be used alone or in combination. Examples of glass used for the support include float glass, tempered glass, colored glass, and heat-shielding glass. If the support is intended for use in heat reflection applications, it is preferably transparent, but it may contain the absorbent described above or a colorant described below. The thickness of the support is preferably 0.05 mm to 5 mm from the viewpoint of ensuring strength and reducing weight. When the laminate includes multiple supports, these supports may be the same or different.

[0056] The intermediate layer serves to bond the dielectric multilayer film of the present invention to the support, colored layer, etc. Examples of adhesives that can be used as the intermediate layer include vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, ethylene-vinyl acetate copolymers, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl ether, nitrile rubbers, styrene-butadiene rubbers, natural rubbers, chloroprene rubbers, polyamides, epoxy resins, polyurethanes, acrylic resins, cellulose, polyvinyl chloride, polyacrylic esters, and polyisobutylene. These adhesives in film form or formed on the surface of a film can also be used as an adhesive. These adhesives may also contain additives such as viscosity adjusters, plasticizers, heat stabilizers, antioxidants, UV absorbers, antistatic agents, lubricants, colorants, and crosslinking agents. When a laminate contains multiple intermediate layers, these intermediate layers may be the same or different. By providing an intermediate layer, it is possible to improve the adhesion between the support or the like and the dielectric multilayer film, and the design, durability, weather resistance, impact resistance, etc. of the laminate. From the viewpoint of improving processability and adhesion as an intermediate layer, the thickness of the intermediate layer is preferably 10 μm to 1 mm.

[0057] The weather-resistant resin layer in the laminate of the present invention is a resin layer provided mainly for the purpose of protecting the dielectric multilayer film, and is preferably a resin layer having an ultraviolet absorbing function. The resin forming the weather-resistant resin layer is not particularly limited, and for example, an acrylic resin, a urethane resin, a polyester resin, a silanol resin, etc. can be used alone or in combination.

[0058] Taking acrylic resins as an example, it is preferable to use, alone or in combination, for example, methacrylic acid, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, 4-hydroxybutyl methacrylate glycidyl ether, phenyl glycidyl acrylate, epoxy acrylate, epoxy methacrylate, dipentaerythritol hexaacrylate, and the like.

[0059] It is also preferable that a hydrophilic monomer be polymerized to impart hydrophilicity to these acrylic resins, and for example, a radically polymerizable vinyl monomer is preferably polymerized. Examples of hydrophilic radically polymerizable vinyl monomers include hydroxyacrylic acid esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; glycol esters such as ethylene glycol acrylate, ethylene glycol methacrylate, polyethylene glycol acrylate, and polyethylene glycol methacrylate; acrylamide compounds such as acrylamide, methacrylamide, N-methylolacrylamide, and methoxymethylolacrylamide; cationic monomers such as aminoalkyl acrylate, aminoalkyl methacrylate esters, and quaternary ammonium salts thereof; glycidyl acrylate compounds such as glycidyl acrylate and glycidyl methacrylate; and unsaturated acids and salts thereof such as acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, and crotonic acid. These may be polymerized singly or in combination.

[0060] Furthermore, it is preferable that the acrylic resin contains an initiator, a curing agent, a catalyst, etc., since this further accelerates curing. The initiator is preferably one that can initiate or accelerate polymerization, condensation, or crosslinking reactions by anion, cation, radical reaction, etc. Various initiators, curing agents, and catalysts can be used. Among these, photopolymerization initiators are preferably used, and alkylphenone compounds are preferred from the viewpoint of curability. Specific examples of alkylphenone compounds include 1-hydroxy-cyclohexyl-phenyl-ketone, 2.2-dimethoxy-1.2-diphenylethan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-phenyl)-1-butane, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-phenyl)-1- butane, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butane, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butane, 1-cyclohexyl-phenyl ketone, 2-methyl-1-phenylpropan-1-one, 1-[4-(2-ethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, etc. Examples of the ultraviolet absorber used in the weather-resistant resin layer include benzotriazole-based, benzophenone-based, benzoate-based, triazine-based, benzoxazinone-based, salicylic acid-based, and indole-based ultraviolet absorbers, and among these, benzotriazole-based and triazine-based ultraviolet absorbers are preferred.

[0061] Molding methods for obtaining laminates using the above-mentioned support, intermediate layer, dielectric multilayer film, and colored layer include extrusion lamination, hot melt lamination, thermal lamination, press lamination, vacuum lamination, autoclave lamination, etc. Extrusion lamination is a method in which molten resin compositions for obtaining the dielectric multilayer film and the intermediate layer are extruded from a die into a film shape, laminated on a support, and then molded by passing the molded product between two rolls. Hot melt lamination is a molding method in which a resin composition for forming the intermediate layer, which has been melted by heat, is applied to the dielectric multilayer film or the support, and the dielectric multilayer film and the support are laminated. Thermal lamination is a molding method in which the dielectric multilayer film, a sheet for the intermediate layer, and the support are heated and pressed together with a heated roll to laminate them. Press lamination is a molding method in which the dielectric multilayer film, a sheet for the intermediate layer, and the support are heated and pressed together with a press to laminate them. Vacuum lamination is a molding method in which a dielectric multilayer film, an intermediate layer sheet, and a support are heated, then the inside of the device is evacuated, and they are pressed and laminated. Autoclave lamination is a lamination method in which a dielectric multilayer film, an intermediate layer sheet, and a support are heated, then the inside of the device is pressurized with gas or the like to laminate. Among these, press lamination, vacuum lamination, and autoclave lamination are preferably used.

[0062] It is important that the water contact angle of the laminate of the present invention on the X-plane, which is the surface opposite the colored layer, is 5° or more and 60° or less. The inventors of the present invention have thoroughly investigated the relationship between the reflection wavelength and the phenomenon of water droplets appearing colored. As a result, they have found that, as shown in the above formula (1), the effect of shortening the reflection wavelength when observed from an oblique angle, making it easier to reflect light with wavelengths from yellow to red in the 600 to 800 nm wavelength range, becomes more pronounced as the water contact angle increases. The mechanism behind this is unclear, but it is speculated that it is because the angle of incidence and the angle of refraction in the above formula (1) increase as the contact angle of the water droplet increases.

[0063] If the water contact angle of the X surface is higher than 60°, the water droplets will increase the angle of incidence of the formula (1), causing the water droplets to appear yellow or red, which is undesirable. Since the coloring is less pronounced as the water contact angle of the X surface decreases, the water contact angle of the X surface is preferably 50° or less, more preferably 40° or less, and particularly preferably 30° or less. If the water contact angle of the X surface is 30° or less, the coloring phenomenon caused by water droplets adhering to the X surface is almost completely eliminated. On the other hand, if the water contact angle of the X surface is less than 5°, it becomes difficult to remove water droplets adhering to the X surface when used in automobiles or windowpanes. Here, the "surface opposite the colored layer" refers to the outermost surface of the dielectric multilayer film opposite the side where the colored layer is located, and this is the X surface. The water contact angle in the present invention can be measured as the water contact angle of pure water after leaving the film in an atmosphere at room temperature of 23°C and a relative humidity of 65% for 24 hours. The detailed measurement method will be described later.

[0064] To achieve a water contact angle of 5° to 60° or within the above-mentioned preferred range on the X-face, it is effective to use a highly hydrophilic material for forming the X-face. Generally, automobile sunroofs and windowpanes are coated with a water-repellent coating to increase the water contact angle above 60° in order to reduce staining caused by water droplets. However, this technique cannot be used in the present invention, which uses a dielectric multilayer film, due to the aforementioned discoloration caused by water droplets. For example, when a substrate or a coating layer on the substrate is located on the X-face of the laminate, polycarbonate is preferably used in automobile sunroof applications to reduce the weight and center of gravity of the vehicle body and improve processability. When using polycarbonate as the substrate, the water contact angle of the surface of these layers (corresponding to the X-face) can be increased to 5° to 60° by providing a hydrophilic hard coat layer (e.g., an acrylic resin layer, a polyester resin layer, a urethane resin layer) on the surface or by forming a photocatalytic layer (e.g., a titanium oxide layer, a tin oxide layer) on the surface. Plasma treatment or corona discharge treatment is also effective in adjusting the water contact angle of the X surface to 5° or more and 60° or less. When a weather-resistant resin layer is located on the outermost surface opposite the colored layer, in order to adjust the water contact angle of the X surface to 5° or more and 60° or less, it is preferable to use a resin in which the aforementioned hydrophilic monomer is polymerized in the weather-resistant resin layer, and for example, it is preferable to polymerize a radically polymerizable vinyl monomer. Even when glass is used as the support, the water contact angle of the X surface can be adjusted to 5° or more and 60° or less by forming the aforementioned hydrophilic hard coat layer or photocatalytic layer.

[0065] The laminate of the present invention preferably has a saturation of 20 or less of reflected light when irradiated onto the X surface. As described above, the colored layer is preferably black, and therefore, when used as a sunroof, low saturation is required when viewed from outside the vehicle. Furthermore, from the viewpoint of suppressing the phenomenon of appearing colored when water droplets adhere, which will be described later, it is preferable to lower the saturation of the laminate itself. If the saturation of reflected light when irradiated onto the X surface is lower than 20, the coloring becomes less noticeable when viewed from the X surface side. From the above viewpoints, the saturation is more preferably 15 or less, even more preferably 10 or less, and particularly preferably 5% or less.

[0066] In order to make the chroma of the reflected light when the X surface is irradiated with light 20 or less or within the above-mentioned preferred range, it is effective to use, for example, a laminated film that simultaneously satisfies the above formula (1) and formula (2) as the dielectric multilayer film. Furthermore, when a metal layer is used as the dielectric multilayer film, the chroma of the reflected light can be reduced by using a light-colored component or by reducing the thickness. The chroma of the reflected light can be measured using a spectrophotometer, and the measurement method will be described in detail later.

[0067] In the laminate of the present invention, the distance from the X plane to the dielectric multilayer film is preferably 0.001 mm or more and 2.0 mm or less. This configuration makes it possible to reduce the coloring that appears when water droplets adhere to the X plane of the laminate. While the reason for this is unclear, it is presumed that the longer the distance from the X plane to the dielectric multilayer film, the greater the angle of incidence of light incident on the dielectric multilayer film, making it easier to reflect light with wavelengths of 600 to 800 nm, from yellow to red. When the distance from the X plane to the dielectric multilayer film is 0.001 mm or more, the thickness of the member responsible for protecting the dielectric multilayer film is sufficiently ensured. On the other hand, when the distance from the X plane to the dielectric multilayer film is 2.0 mm or less, the distance from the X plane to the dielectric multilayer film is shortened, thereby effectively reducing the coloring that appears when water droplets adhere to the dielectric multilayer film. To achieve a distance from the X plane to the dielectric multilayer film of 0.001 mm or more and 2.0 mm or less, it is effective to keep the total thickness of the members located between the X plane and the dielectric multilayer film within the above range.

[0068] Next, a preferred method for producing a laminate film that can be suitably used as the dielectric multilayer film of the laminate of the present invention will be described below using an example in which a crystalline polyester resin is used as the thermoplastic resin A (layer A) and an amorphous polyester resin is used as the thermoplastic resin B (layer B). Of course, the present invention is not limited to this example. Furthermore, the formation of the laminate structure of the laminate film itself can be realized by referring to the description in paragraphs

[0053] to

[0063] of JP-A-2007-307893. The same can be said for a laminate film consisting of three types of layers, including layer C.

[0069] First, thermoplastic resin A and thermoplastic resin B are prepared in the form of pellets or the like. If necessary, the pellets are dried in hot air or under vacuum and then fed into separate extruders. In the extruder, thermoplastic resin A is heated and melted at a temperature above its melting point, and thermoplastic resin B is heated and melted at a temperature within ±30°C of the heating temperature of thermoplastic resin A (this temperature range may be adjusted as needed to prevent uneven extrusion). The molten thermoplastic resin is then extruded at a uniform extrusion rate using a gear pump or the like, and foreign matter and denatured resin are removed using a filter or the like. These molten thermoplastic resins are laminated in the desired layer configuration using a lamination device, formed into the desired sheet shape using a die, and then discharged onto a casting drum. The multilayered molten sheet discharged from the die is then extruded onto a cooling body such as a casting drum and cooled and solidified to obtain a cast film. In this process, it is preferable to use a wire-, tape-, needle-, or knife-shaped electrode to electrostatically contact the casting drum or other cooling body for rapid solidification. Also preferred are methods in which air is blown from a slit-, spot-, or planar-shaped device to bring the molten sheet into close contact with a cooling body such as a casting drum for rapid solidification, or nip rolls to bring the molten sheet into close contact with a cooling body for rapid solidification. The surface temperature of the cooling body such as a casting drum is preferably 5°C or higher and 30°C or lower from the viewpoint of rapidly cooling and solidifying the molten sheet.

[0070] As a lamination device, a multi-manifold die, a feed block, a static mixer, etc. can be used. However, in order to efficiently obtain the configuration of the present invention, it is particularly preferable to use a feed block containing at least two or more separate members with multiple fine slits. The use of such a feed block prevents the device from becoming excessively large, reduces the amount of foreign matter caused by thermal degradation, and enables high-precision lamination even when the number of layers is extremely large. Furthermore, the lamination accuracy in the width direction is significantly improved compared to conventional technology. Furthermore, with such a device, the thickness of each layer can be adjusted by the shape (length, width) of the slits, making it easy to achieve any desired layer thickness.

[0071] The cast film thus obtained is then preferably biaxially stretched. Here, biaxial stretching refers to stretching in the longitudinal direction and the width direction. Stretching may be performed in two directions sequentially or simultaneously. Furthermore, re-stretching may be performed in the longitudinal direction and / or the width direction. The longitudinal direction refers to the running direction of the film, and the width direction refers to the direction perpendicular to the longitudinal direction within the film plane.

[0072] First, we will explain the case of sequential biaxial stretching. Here, stretching in the longitudinal direction (longitudinal stretching) refers to stretching to impart molecular orientation to the film in the longitudinal direction, and is usually performed by varying the peripheral speed of rolls. This stretching can be performed in one stage, or in multiple stages using multiple pairs of rolls. The stretching ratio varies depending on the type of thermoplastic resin constituting the laminate film, but is usually preferably 2.0 to 9.0 times. When a polyethylene naphthalate copolymer resin is used as one of the thermoplastic resins constituting the laminate film, a ratio of 2.0 to 7.0 times is preferably used, and 3.0 to 3.8 times is more preferred. The surface temperature of the film during stretching is preferably in the range of the glass transition temperature of the resin with the higher glass transition temperature constituting the laminate film to the glass transition temperature + 100°C.

[0073] The uniaxially stretched film thus obtained may be subjected to a surface treatment such as corona treatment, flame treatment, or plasma treatment as needed, and then may be imparted with properties such as easy slippage, easy adhesion, and antistatic properties by in-line coating.

[0074] Width-direction stretching (transverse stretching) refers to stretching to impart width-direction orientation to a film. Typically, a tenter is used to convey a uniaxially stretched film while holding both ends with clips, thereby stretching it in the width direction. The stretching ratio varies depending on the type of resin, but is typically preferably 2.0 to 9.0 times. When a polyethylene naphthalate copolymer resin is used as one of the resins constituting the laminate film, a ratio of 2.0 to 7.0 times is preferred, with 3.7 to 4.2 times being more preferred. The in-plane stretching ratio, which is the product of the longitudinal stretching ratio and the transverse stretching ratio, is preferably 12.0 to 18.0 times. The stretching temperature is preferably in the range of the glass transition temperature of the resin with the higher glass transition temperature constituting the laminate film to the glass transition temperature + 120°C.

[0075] The biaxially stretched film thus obtained is preferably heat-treated in a tenter at a temperature equal to or higher than the stretching temperature and equal to or lower than the melting point of thermoplastic resin A to impart flatness and dimensional stability. Heat treatment improves the dimensional stability of the resulting laminated film. After heat treatment in this manner, the laminated film is gradually cooled uniformly at a temperature equal to or higher than the glass transition temperature of thermoplastic resin A and lower than the heat treatment temperature, then cooled to room temperature and wound up. Furthermore, additional stretching of 0.1% to 10% or relaxation treatment may be performed in combination during the period from heat treatment to gradual cooling.

[0076] Furthermore, in the laminate film of the present invention, the heat treatment temperature after stretching is preferably set to be equal to or lower than the melting point of thermoplastic resin A and equal to or higher than the melting point of thermoplastic resin B. In this case, thermoplastic resin A maintains a high degree of orientation while the orientation of thermoplastic resin B is relaxed, making it easy to achieve a refractive index difference between the layers (layer A, layer B) containing these resins as their main components. When an amorphous resin is used as either thermoplastic resin A or thermoplastic resin B, the heat treatment temperature is preferably equal to or lower than the melting point of the crystalline resin and in the range of the glass transition temperature of the crystalline resin to the glass transition temperature + 120°C. When at least one of thermoplastic resin A and thermoplastic resin B is a crystalline polyester containing naphthalenedicarboxylic acid units as its main structural unit, the heat treatment temperature is preferably equal to or higher than 170°C and lower than 220°C.

[0077] Next, simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the obtained cast film may be subjected to a surface treatment such as corona treatment, flame treatment, or plasma treatment as necessary, and then may be imparted with properties such as easy lubricity, easy adhesion, and antistatic properties by in-line coating.

[0078] Next, while holding both widthwise ends with clips, the cast film is introduced into a simultaneous biaxial tenter and conveyed there, where it is stretched simultaneously and / or stepwise in the longitudinal and widthwise directions. Simultaneous biaxial stretching machines include pantograph, screw, drive motor, and linear motor types. Drive motor and linear motor types are preferred, as they allow for arbitrary stretching ratio adjustment and relaxation treatment at any desired location. The stretching ratio varies depending on the type of resin, but an area ratio of 6.0 to 30.0 times is typically preferred. When a polyethylene naphthalate copolymer resin is used as one of the resins constituting the laminate film, an area ratio of 9.0 to 18.0 times is particularly preferred. In particular, in the case of simultaneous biaxial stretching, it is preferable to maintain the same stretching ratio in the longitudinal and widthwise directions and to ensure that the stretching speeds are approximately equal to each other in order to suppress in-plane orientation differences. Furthermore, the stretching temperature is preferably within the range of the glass transition temperature of the resin with the higher glass transition temperature constituting the laminate film to the glass transition temperature + 120°C.

[0079] The biaxially stretched film is then heat-treated, slowly cooled, and cooled to room temperature before being wound up, as in the case of sequential biaxial stretching. During the heat treatment, it is preferable to instantly relax the film in the longitudinal direction immediately before and / or after entering the heat treatment zone in order to suppress the distribution of the main orientation axis in the width direction. [Example]

[0080] The laminated film of the present invention will be described in more detail below using examples, but the laminated film of the present invention is not limited to the embodiments shown below.

[0081] [Methods for measuring physical properties and evaluating effects] The evaluation methods for the characteristic values ​​and the effects are as follows.

[0082] (1) Layer thickness, number of layers, and layer configuration The layer structure and number of layers of the dielectric multilayer film were identified, and the thickness of each layer was measured using a transmission electron microscope (TEM) with cross-sections of samples cut out using a microtome, followed by observation and length measurement. Specifically, a transmission electron microscope H-7100FA (Hitachi, Ltd.) was used to observe the cross-section of the film at 10,000 to 40,000 times magnification at an accelerating voltage of 75 kV, and cross-sectional photographs were taken. The layer structure and number of layers were identified, and the thickness of each layer was measured. In some cases, known staining techniques using RuO4, OsO4, etc. were used to enhance the contrast between layers.

[0083] (2)Reflectance Reflectance measurements were performed under the following conditions using a Hitachi spectrophotometer (U-4100 Spectrophotometer) with an integrating sphere attached. The sample was placed behind the integrating sphere with its longitudinal axis facing up and down during the reflectance measurement, and the reflectance was calculated as the relative reflectance based on the aluminum oxide secondary white plate attached to the instrument. The average reflectance was calculated by averaging all the reflectance values ​​at 1 nm intervals. Measurements were performed on both sides of the sample, and the measurement results for the side with the higher average reflectance at wavelengths between 900 and 1000 nm were used. <Measurement conditions> Slit: 2nm (visible) / Automatic control (infrared) Gain: 2 Scanning speed: 600 nm / min Starting wavelength: 2600nm End wavelength: 240nm Sampling interval: 1 nm Incident angle: 10°.

[0084] (3) Melting point, glass transition temperature, crystallization temperature, heat of crystal fusion A 5 g sample was taken, and the melting point, glass transition temperature, crystallization temperature, and heat of crystalline fusion were measured and calculated using a differential scanning calorimeter (Robot DSC-RDC220 manufactured by Seiko Instruments Inc.) in accordance with JIS-K-7121 (1987). For the measurements, the sample was heated from 25°C to 290°C at a rate of 5°C / min.

[0085] (4) Water contact angle on the X surface The laminate was left for 24 hours in an atmosphere at room temperature of 23°C and relative humidity of 65%. After that, in the same atmosphere, the contact angle of pure water was measured at five arbitrarily selected points on the X surface using a contact angle meter CA-D model (manufactured by Kyowa Interface Science Co., Ltd.). The average value of the three measurements excluding the maximum and minimum values ​​of the five measurements was taken as the water contact angle of the X surface.

[0086] (5) Appearance of laminate (Observation when water droplets are attached) The laminate was placed under a three-band fluorescent lamp, and the water droplets attached in (4) were visually observed and evaluated from angles of 0°, 45°, and 70° relative to the normal direction. The evaluation criteria were as follows, with ⊚ and ◯ representing good results. ◎: The entire water droplet was colored and not visible. ○: Some of the water droplets appeared slightly colored. ×: The entire water droplet appeared to be colored, or only a portion of the water droplet appeared to be clearly colored.

[0087] (6) Colorimetry (reflection saturation, transmission L*) The spectrophotometer used was a CM-3600d manufactured by Konica Minolta Sensing, Inc. For reflection saturation, the saturation of the X-plane was measured using the SCI method in reflection object color measurement mode under conditions of a target mask with a measurement diameter of 8 mm, and the average value was calculated for an n number of 5. For transmission L*, L* was measured in transmission measurement mode under conditions of a target mask with a measurement diameter of 25.4 mm, and the average value was calculated for an n number of 5. Calibration was performed using the white calibration plate and zero calibration box listed below. D65 was selected as the light source used to calculate the colorimetric values. White calibration plate: CM-A103 Zero calibration box: CM-A104.

[0088] (7) Temperature increase due to external light The laminate was placed parallel to the glass bulb of a Panasonic "RF100V200W-W / D" reflector bulb at a position 30 cm from the tip of the bulb, and the light was irradiated at a temperature of 25°C and humidity of 60%RH. A thermometer was inserted 2 cm from the laminate on the opposite side of the reflector bulb, and the temperature was measured 2 minutes after irradiation. [Resin used in manufacturing the dielectric multilayer film] In manufacturing the dielectric multilayer film, the following resins were used as thermoplastic resins for layers A and B. Note that among the thermoplastic resins used for layers A and B, all those not described as amorphous are crystalline thermoplastic resins.

[0089] (Thermoplastic resin for layer A) PEN(1): Polyethylene 2,6-naphthalate copolymerized with 6 mol% polyethylene glycol having an average molecular weight of 400 relative to the total diol components (intrinsic viscosity: 0.64, melting point: 255°C, glass transition temperature: 97°C).

[0090] (Thermoplastic resin for layer B) PET (1): A mixture of polyethylene terephthalate resin (intrinsic viscosity: 0.73, amorphous resin (no melting point), glass transition temperature: 79°C) copolymerized with 31 mol% cyclohexanedimethanol (CHDM) relative to the total diol constituents, and polyethylene terephthalate (manufactured by Toray Industries, Inc., intrinsic viscosity: 0.65, melting point: 256°C, glass transition temperature: 80°C) in a mass ratio of 82:18 (melting point: 225°C, glass transition temperature: 79°C). PET (2): Polyethylene terephthalate resin copolymerized with 31 mol% cyclohexanedimethanol (CHDM) relative to the total diol constituents (intrinsic viscosity: 0.73, amorphous resin (no melting point), glass transition temperature: 79°C) and polyethylene terephthalate (manufactured by Toray Industries, Inc., intrinsic viscosity: 0.65, melting point: 256°C, glass transition temperature: 80°C) mixed in a mass ratio of 50:50 (melting point: 225°C, glass transition temperature: 79°C). PET (3): Polyethylene terephthalate resin copolymerized with 31 mol% cyclohexanedimethanol (CHDM) relative to the total diol constituents (intrinsic viscosity: 0.73, amorphous resin (no melting point), glass transition temperature: 79°C) and polyethylene terephthalate (manufactured by Toray Industries, Inc., intrinsic viscosity: 0.65, melting point: 256°C, glass transition temperature: 80°C) mixed in a mass ratio of 30:70 (melting point: 230°C, glass transition temperature: 80°C). PET (4): Polyethylene terephthalate resin copolymerized with 30 mol% of 2,6-naphthalenedicarboxylic acid relative to the total dicarboxylic acid constituents (intrinsic viscosity: 0.67, amorphous resin (no melting point), glass transition temperature: 95°C).

[0091] [Materials used as support] The following materials were used as supports. In the preparation of a laminate having supports on the outermost surfaces of both sides, corona discharge treatment and formation of a hard coat layer were performed on only one surface of one of the supports, and the surface subjected to these treatments was positioned on the surface opposite the colored layer (X surface) (however, when these treatments were not performed, the outermost surface was arbitrary). In other words, the surface opposite the X surface was made of the following material that had not been subjected to these treatments. PC (1): Polycarbonate with a thickness of 5 mm was used. Corona discharge treatment was performed for 5 seconds, and the water contact angle was 58°. PC (2): Polycarbonate with a thickness of 5 mm was used. Corona discharge treatment was performed for 30 seconds, and the water contact angle was 49°. PC (3): A 5 mm thick polycarbonate was used. A mixture of 15% by weight of acrylic ester, 15% by weight of epoxy acrylate, 15% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater and then irradiated with ultraviolet light to form a hard coat layer. The hard coat layer had a thickness of 3 μm and a water contact angle of 38°. PC (4): A 5 mm thick polycarbonate was used. A mixture of 35% by weight of 2-hydroxyethyl methacrylate, 10% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater and then irradiated with ultraviolet light to form a hard coat layer. The hard coat layer had a thickness of 3 μm and a water contact angle of 25°. Glass (1): A 5 mm thick float glass was used. A mixture of 10% by weight of acrylic ester, 35% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater, and a hard coat layer was formed by ultraviolet irradiation. The hard coat layer had a thickness of 3 μm and a water contact angle of 57°. Glass (2): A 5 mm thick float glass was used. A mixture of 15% by weight of acrylic ester, 15% by weight of epoxy acrylate, 15% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater and then irradiated with ultraviolet light to form a hard coat layer. The hard coat layer had a thickness of 3 μm and a water contact angle of 38°. Glass (3): A 5 mm thick float glass was used. A mixture of 45% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater, and a hard coat layer was formed by ultraviolet irradiation. The hard coat layer had a thickness of 3 μm and a water contact angle of 64°. Weather-resistant resin layer (1): A mixture of 45% by weight of urethane acrylate, 1% by weight of the photoinitiator "Irgacure" (registered trademark) 184, 34% by weight of methyl ethyl ketone, and 20% by weight of propylene glycol monomethyl ether acetate was applied with a bar coater and irradiated with ultraviolet light to form a weather-resistant resin layer. The thickness was 3 μm, and the water contact angle was 58°. PC (5): Polycarbonate with a thickness of 3 mm was used. Corona discharge treatment was performed for 5 seconds, and the water contact angle was 58°. PC (6): Polycarbonate with a thickness of 2 mm was used. Corona discharge treatment was performed for 5 seconds, and the water contact angle was 58°. PC (7): Polycarbonate with a thickness of 5 mm was used. The water contact angle was 85°C.

[0092] [Colored layer] Colored layer 1: PVB (polyvinyl butyral) with a thickness of 0.8 mm and containing dispersed carbon black was used. Colored layer 2: Polycarbonate with a thickness of 5 mm and dispersed carbon black was used. Colored layer 3: Float glass with a thickness of 5 mm and dispersed with carbon black was used.

[0093] Example 1 PEN (1) was used as the polyester resin (thermoplastic resin A) forming layer A, and PET (1) was used as the polyester resin (thermoplastic resin B) forming layer B. The polyester resins forming each layer were melted at 280°C in a vented twin-screw extruder and then merged in a 449-layer feed block via a gear pump and filter. A total of 449 layers of molten thermoplastic resins A and B were laminated alternately in the thickness direction, with layer A being the outermost layer on both sides. The resulting molten laminate was then guided to a T-die, formed into a sheet, and extruded. The molten sheet was electrostatically quenched and solidified on a casting drum at a surface temperature of 25°C to obtain a cast film. The extrusion rate was adjusted so that the thickness ratio of adjacent layers A and B (thickness of layer A / thickness of layer B) was approximately 0.9. The resulting cast film was then heated using a group of rolls set at a temperature 10°C above the glass transition temperature of thermoplastic resin A. It was then rapidly heated from both sides using a radiation heater within a 100mm stretching section, stretched 3.2 times in the machine direction (longitudinal direction) while maintaining a film surface temperature of 10°C above the glass transition temperature of thermoplastic resin A, and then cooled. Both sides of this uniaxially stretched film were then subjected to a corona discharge treatment in air to set the wetting tension to 55mN / m, and a lamination coating solution consisting of (polyester resin with a glass transition temperature of 18°C) / (polyester resin with a glass transition temperature of 82°C) / silica particles with an average particle size of 100nm (median diameter determined by laser diffraction and scattering according to JIS Z 8825 (2022)) was applied to both sides to form a transparent, slippery, and easy-to-adhere layer. This uniaxially stretched film was held at both widthwise ends with clips and introduced into a tenter. After preheating with hot air at 100°C, it was stretched 4.0 times in the transverse direction (widthwise direction) at a temperature 20°C above the glass transition temperature of thermoplastic resin A at a uniform stretching speed. Furthermore, in the same tenter, the stretched film was heat-treated with hot air at 195°C and subjected to a 1% relaxation treatment in the widthwise direction at the same temperature. It was then further stretched 1% in the widthwise direction in a cooling zone at 150°C, slowly cooled to room temperature, and wound up. The thickness of the resulting dielectric multilayer film was 90 μm.

[0094] The laminate was prepared using a Nisshinbo LAMINATOR 0303S. The laminated components were heated from 25°C to 150°C at a rate of 3°C / min as shown in Table 1, then the pressure was reduced to 600 mmHg for 5 minutes and the components were pressed at a pressure of 0.1 MPa for 30 minutes. The components were then slowly cooled to 35°C at a rate of 3°C / min while still pressed, and the press was released to obtain a laminate. The evaluation results of the resulting laminate are shown in Table 1.

[0095] (Examples 2 to 9, 11 to 19, Comparative Examples 1 to 9) A laminate was produced under the same conditions as in Example 1, except that the configuration of the dielectric multilayer film used for each layer and the configuration of the laminate were changed as shown in Tables 1 and 2. The evaluation results of the obtained laminate are shown in Tables 1 and 2. The number of layers was adjusted by adjusting the number of slits in the feed block, and the thickness was adjusted by changing the speed of the entire film production line linked to the casting drum speed.

[0096] Example 10 Except for providing the weather-resistant resin layer (1) on the dielectric multilayer film as described above, a laminate was obtained under the same conditions as in Example 1. The evaluation results of the obtained laminate are shown in Table 1.

[0097] Example 20 A laminate was obtained under the same conditions as in Example 1, except that a 10 nm thick indium oxide layer (metal layer (1)), a 12 nm thick silver thin film layer (metal layer (2)), and a 20 nm thick indium oxide layer were formed in this order by sputtering on "Toughtop" (registered trademark) C0T0 (100 μm thick) manufactured by Toray Advanced Film Co., Ltd., which is a film having an acrylic hard coat. The evaluation results of the obtained laminate are shown in Table 1.

[0098] [Table 1]

[0099] [Table 2] [Industrial Applicability]

[0100] The present invention can be used in decorative materials such as decorative panels, various home appliances, building materials, automobile parts, etc., and can be particularly used as heat-blocking glass that can suppress the inflow of heat caused by sunlight.

Claims

1. A laminate having a colored layer on one side of a dielectric multilayer film, wherein Ra is an average reflectance in the wavelength range of 900 to 1000 nm and Rb is an average reflectance in the wavelength range of 400 to 700 nm, and Ra is 50% or more and 100% or less; the shortest wavelength that is an intermediate value between Ra and Rb in the wavelength range of 700 to 900 nm is 850 nm or more; and when the surface opposite to the colored layer is defined as an X-plane, the water contact angle of the X-plane is 5° or more and 60° or less.

2. 2. The laminate according to claim 1, wherein the saturation of reflected light when the X-face is irradiated with light is 20 or less.

3. 3. The laminate according to claim 1, wherein the difference between the Ra and the Rb is 20% or more and 90% or less.

4. 3. The laminate according to claim 1, wherein the dielectric multilayer film is a laminate film containing a thermoplastic resin as a main component.

5. The laminate according to claim 4, wherein the laminate film has a structure in which at least 51 layers of at least two types of layers each having a different thermoplastic resin as a main component are regularly laminated.

6. 3. The laminate according to claim 1, wherein the distance from the X-plane to the dielectric multilayer film is 0.001 mm or more and 2.0 mm or less.

7. 3. The laminate according to claim 1, wherein the maximum reflectance Rd at a wavelength of 400 to 830 nm is 0.1% or more and 15% or less.

8. 3. The laminate according to claim 1, wherein the weather-resistant resin layer, the dielectric multilayer film, the adhesive layer, and the colored layer are arranged in this order, and the colored layer is mainly composed of glass or resin.

9. 3. The laminate according to claim 1, wherein the support, the intermediate layer 1, the dielectric multilayer film, the intermediate layer 2, and the colored layer are arranged in this order, and the colored layer and the support are mainly composed of glass or resin.

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