Laminate

Abstract

To provide a laminate capable of suppressing occurrence of a crack in a dielectric multilayer film due to temperature changes, while also suppressing occurrence of an appearance defect.SOLUTION: A laminate 11 comprises a synthetic resin substrate 12, an acrylic polymer film 13 laminated on a back surface of the substrate 12, and a dielectric multilayer film 14 laminated on the acrylic polymer film 13.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, a known laminate is one shown in Patent Document 1. This laminate includes a synthetic resin substrate, a cured coating film formed on the substrate, a metal thin film layer formed on the cured coating film, and a top coat layer formed on the metal thin film layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-94108 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned laminate, unevenness in the coating when applying the coating material that forms the cured coating film to the substrate can cause an uneven pattern called "yellow peel" on the surface of the cured coating film, which can result in poor appearance. For this reason, if the metal thin film layer is formed directly on the substrate without the cured coating film, the difference in linear expansion coefficient between the substrate and the metal thin film layer becomes large. As a result, there is a problem that cracks occur in the metal thin film layer due to the difference in expansion between the substrate and the metal thin film layer due to temperature changes. [Means for solving the problem]

[0005] Various aspects of the laminate for solving the above problems will be described below. [Embodiment 1] A laminate comprising a substrate made of synthetic resin, an acrylic polymer film laminated on at least one of the front and back surfaces of the substrate, and a dielectric multilayer film laminated on the acrylic polymer film.

[0006] According to the above configuration, the acrylic polymer film does not develop the uneven surface pattern known as orange peel caused by coating film unevenness, as occurs with coating films, and therefore, the occurrence of defects in appearance due to unevenness can be suppressed. In addition, the difference in linear expansion coefficient between the acrylic polymer film and the dielectric multilayer film is smaller than the difference in linear expansion coefficient between the substrate and the dielectric multilayer film. Therefore, by interposing the acrylic polymer film between the substrate and the dielectric multilayer film, the occurrence of cracks in the dielectric multilayer film due to the difference in expansion between the acrylic polymer film and the dielectric multilayer film caused by temperature changes can be suppressed. Therefore, the occurrence of defects in appearance can be suppressed while the occurrence of cracks in the dielectric multilayer film caused by temperature changes can be suppressed.

[0007] [Aspect 2] The laminate according to [Aspect 1], wherein the acrylic polymer film is formed by radicalizing an acrylic monomer with plasma and polymerizing it. According to the above-mentioned configuration, the acrylic polymer film can be formed at a relatively low temperature, so that damage caused by heat can be reduced. [Effects of the Invention]

[0008] The present invention can suppress the occurrence of defects in appearance and also suppress the occurrence of cracks in the dielectric multilayer film due to temperature changes. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of a laminate according to one embodiment. [Figure 2] FIG. 10 is a cross-sectional view of a laminated body according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment will be described below with reference to the drawings. <Laminate 11> 1, the laminate 11 includes a substrate 12, an acrylic polymer film 13 laminated on the back surface of the substrate 12, and a dielectric multilayer film 14 laminated on the back surface of the acrylic polymer film 13. The laminate 11 has a thickness set to, for example, about 1 mm to 5 mm.

[0011] The base material 12 is made of, for example, a synthetic resin that transmits light, such as polycarbonate (PC) or polypropylene (PP).

[0012] The acrylic polymer film 13 is formed by radicalizing an acrylic monomer with plasma and polymerizing it. That is, the acrylic polymer film 13 is formed by the well-known plasma CVD (Chemical Vapor Deposition). Plasma CVD is a method of forming a film by converting a raw material gas into a plasma state to generate active radicals, and then causing a chemical reaction (polymerization). Plasma CVD is a method that allows film formation at a lower temperature than thermal CVD.

[0013] The dielectric multilayer film 14 has a high-refractive index film 15 having a relatively high refractive index and a low-refractive index film 16 having a relatively low refractive index. As an example, the dielectric multilayer film 14 of this embodiment has a structure in which two high-refractive index films 15 and two low-refractive index films 16 are alternately stacked. With this structure, the dielectric multilayer film 14 functions as an anti-reflection film. Note that the high-refractive index films 15 and low-refractive index films 16 are alternately stacked in the dielectric multilayer film 14 so that the low-refractive index film 16 is disposed at the end opposite the substrate 12 in the stacking direction.

[0014] In the dielectric multilayer film 14 of this embodiment, the high refractive index film 15 is made of niobium pentoxide (NbO), and the low refractive index film 16 is made of an acrylic polymer film similar to the acrylic polymer film 13. The high refractive index film 15 and the low refractive index film 16 are formed by the above-mentioned plasma CVD. The high refractive index film 15 of the dielectric multilayer film 14 comes into contact with the acrylic polymer film 13 laminated on the substrate 12.

[0015] The difference in linear expansion coefficient between the acrylic polymer film 13 laminated on the substrate 12 and the high refractive index film 15 of the dielectric multilayer film 14 is smaller than the difference in linear expansion coefficient between the substrate 12 and the high refractive index film 15 of the dielectric multilayer film 14.

[0016] <Durability test> A thermal shock test was conducted in which the laminate 11 was placed indoors and the room temperature was changed between -40°C and 105°C, and no cracks were observed in the laminate 11. Furthermore, when the laminate 11 was placed in a room with a temperature of 80°C and a humidity of 95% and left for 96 hours, no cracks were observed in the laminate 11. Therefore, the laminate 11 has sufficient durability against temperature changes and high-temperature and high-humidity environments.

[0017] <Operation of the embodiment> The laminate 11 is used, for example, in an electromagnetic wave transparent cover placed in front of an in-vehicle laser lidar (LiDAR; light detection and ranging) or millimeter-wave radar. Laser lidar measures the distance and direction to an object by measuring the time it takes for an emitted laser beam to hit the object and bounce back. Millimeter-wave radar measures the distance and direction to an object by measuring the time it takes for an emitted millimeter wave (radio wave) to hit the object and bounce back.

[0018] When the laminate 11 is used for an electromagnetic wave transmission cover, the acrylic polymer film 13 does not produce an uneven pattern called orange peel on the surface due to unevenness of the coating film, as occurs with a coating film. Therefore, the occurrence of defects in appearance due to the uneven pattern of the laminate 11 being visible in the electromagnetic wave transmission cover is suppressed.

[0019] Furthermore, when the laminate 11 is used in a place with large temperature differences, it expands and contracts due to changes in the ambient temperature. However, in the laminate 11, the difference in linear expansion coefficient between the acrylic polymer film 13 laminated on the substrate 12 and the high refractive index film 15 of the dielectric multilayer film 14 is smaller than the difference in linear expansion coefficient between the substrate 12 and the high refractive index film 15 of the dielectric multilayer film 14.

[0020] Therefore, since the laminate 11 has the acrylic polymer film 13 interposed between the substrate 12 and the high refractive index film 15 of the dielectric multilayer film 14, the occurrence of cracks in the high refractive index film 15 of the dielectric multilayer film 14 due to the difference in expansion between the acrylic polymer film 13 and the high refractive index film 15 of the dielectric multilayer film 14 caused by temperature changes is suppressed.

[0021] <Effects of the embodiment> According to the embodiment described above in detail, the following effects are achieved. (1) The laminate 11 includes a substrate 12 made of synthetic resin, an acrylic polymer film 13 laminated on the rear surface of the substrate 12 , and a dielectric multilayer film 14 laminated on the acrylic polymer film 13 .

[0022] According to the above configuration, the operation of the above embodiment can suppress the occurrence of defects in appearance, while also suppressing the occurrence of cracks in the high refractive index film 15 of the dielectric multilayer film 14 due to temperature changes.

[0023] (2) In the laminate 11, the acrylic polymer film 13 is formed by radicalizing an acrylic monomer with plasma and polymerizing it. According to the above-mentioned configuration, the acrylic polymer film 13 can be formed at a relatively low temperature by the above-mentioned plasma CVD, so that damage caused by heat can be reduced.

[0024] <Example of change> The above embodiment can be modified as follows: Furthermore, the above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0025] 2, the laminate 11 may have an acrylic polymer film 13 and a dielectric multilayer film 14 laminated on the front surface side of the substrate 12 in the same manner as on the back surface side. In this case, the laminate 11 has a layer structure symmetrical with respect to the substrate 12. This can further enhance the function of the dielectric multilayer film 14 as an anti-reflection film.

[0026] In the laminate 11, the low refractive index film 16 of the dielectric multilayer film 14 may be made of silicon oxide (SiOx). In the laminate 11, the thicknesses of the substrate 12, the acrylic polymer film 13, the high refractive index film 15, and the low refractive index film 16 may be changed as appropriate.

[0027] The dielectric multilayer film 14 may have at least one high refractive index film 15 and one low refractive index film 16. That is, the dielectric multilayer film 14 may have a configuration in which three or more high refractive index films 15 and three or more low refractive index films 16 are alternately stacked.

[0028] The laminate 11 may be used for a front grille of a vehicle, an emblem of a vehicle, an in-vehicle screen, a screen of a smartphone, or the like. [Explanation of symbols]

[0029] 11...Laminate 12...Base material 13...Acrylic polymer film 14...Dielectric multilayer film 15...High refractive index film 16...Low refractive index film

Claims

1. A synthetic resin base material; an acrylic polymer film laminated on at least one of the front and back surfaces of the substrate; a dielectric multilayer film laminated on the acrylic polymer film; A laminate comprising:

2. 2. The laminate according to claim 1, wherein the acrylic polymer film is formed by radicalizing an acrylic monomer with plasma and polymerizing the radical.

Images