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EP-3564717-B1 - LAYERED FILM HAVING ANTIREFLECTION FUNCTION AND INFRARED-SHIELDING FUNCTION

EP3564717B1EP 3564717 B1EP3564717 B1EP 3564717B1EP-3564717-B1

Inventors

  • HASHIMOTO, TAKETO

Dates

Publication Date
20260506
Application Date
20171129

Claims (10)

  1. A laminated film having a heat-ray shielding layer (2) and a low-refractive-index layer (1) in this order on at least one surface of a resin film (3, 4, 5), wherein a difference (Rh - Rf) between a refractive index (Rh) of the heat-ray shielding layer (2) and a refractive index (Rf) of the resin film (3, 4, 5) is -0.1 to 0.1; the refractive index (Rf) of the resin film (3, 4, 5) is 1.40 to 1.60; a difference (Rh - RL) between the refractive index (Rh) of the heat-ray shielding layer (2) and a refractive index (RL) of the low-refractive-index layer (1) is 0.05 or more; the refractive index (RL) of the low-refractive-index layer (1) is 1.2 or more and less than 1.45; the heat-ray shielding layer (2) is formed from a coating material comprising: (A) 100 parts by mass of a polyfunctional (meth)acrylate; and (B) 50 parts by mass or more of a heat-ray shielding material which includes fine particles; the amount of the heat-ray shielding material of component (B) is with respect to 100 parts by mass of the polyfunctional (meth)acrylate of component (A); the heat-ray shielding material has an average particle diameter of 1 to 300 nm; and the average particle diameter of the heat-ray shielding material is a particle diameter at which a cumulative value from the smallest particle diameter reaches 50% by mass in a particle diameter distribution curve measured using a laser diffraction/scattering particle size analyzer.
  2. The laminated film according to claim 1, wherein the heat-ray shielding material comprises at least one selected from the group consisting of fine particles of tin-doped indium oxide, antimony-doped tin oxide, cesium-doped tungsten oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, and niobium-doped titanium oxide.
  3. The laminated film according to claim 1 or 2, wherein the heat-ray shielding layer (2) is formed of a coating material comprising: (A) 100 parts by mass of the polyfunctional(meth)acrylate; and (B) 50 to 400 parts by mass of the heat-ray shielding material.
  4. The laminated film according to any one of claims 1 to 3, wherein the refractive index (RL) of the low-refractive-index layer (1) is 1.2 to 1.4.
  5. The laminated film according to any one of claims 1 to 4, wherein a visible-light transmittance is 88% or more.
  6. The laminated film according to any one of claims 1 to 5, wherein the refractive index (Rh) of the heat-ray shielding layer (2) is 1.40 to 1.65.
  7. The laminated film according to any one of claims 1 to 6, wherein a thickness of the heat-ray shielding layer (2) is 0.1 to 5 µm.
  8. The laminated film according to any one of claims 1 to 7, wherein in a reflectance spectrum of visible light at a wavelength of 380 to 780 nm, a difference in reflectance between the top of a waveform around a wavelength with the lowest reflectance and the bottom of a waveform adjacent thereto is 1.0% or less, or above 1.0% and 1.5% or less.
  9. An article comprising the laminated film according to any one of claims 1 to 8.
  10. A building window glass, a car roof window, or a car front window comprising the laminated film according to any one of claims 1 to 8.

Description

TECHNICAL FIELD The present invention relates to a laminated film having an antireflection function and an infrared-shielding function. BACKGROUND ART Conventionally, a transparent film having an infrared-shielding function has been often pasted on, for example, a building window glass and a car roof window from a viewpoint of making a space comfortable using less energy. In recent years, such transparent infrared-shielding film has been applied to a car front window. On the other hand, the transparent infrared-shielding film applied to a car front window has been required to have very highly transparency by legal restraints from a viewpoint of safety. Therefore, the market has required that the transparent infrared-shielding film further improve a balance between the infrared-shielding function and transparency. Further, when a transparent infrared-shielding film is applied to a car front window, the transparent infrared-shielding film has been required to further have an antireflection function and prevent a decrease in visibility due to the reflection of light thrown from the side or rear of the driver seat also from a viewpoint of safety. Films having an antireflection function and an infrared-shielding function are suggested in, for example, Patent Literature 1 and Patent Literature 2. In techniques in Patent Literature 1 and Patent Literature 2, however, transparency is insufficient to apply the films to a car front window. Moreover, the techniques in the literatures do not have measures against reflection color irregularities at all. JP-A-2012-121277 addresses the problem of providing a heat-ray shielding glass that has superior heat-ray shielding properties, especially, thermal insulation, is manufactured at low cost, has high visible light transmittance, and has durability in the presence of water. The disclosed heat-ray shielding glass includes: a glass plate; and a heat-ray reflective layer disposed on a surface of the glass plate and made of a conductive polymer. A low-refractive index layer is formed on a surface of the heat-ray reflective layer, and a refractive index of the low-refractive index layer is lower than that of the heat-ray reflective layer. A double-glazed glass using the heat-ray shielding glass is also disclosed. JP-A-2010-164713 addresses the problem of providing a near-infrared ray absorption hard coat film which has excellent brightness contrast even when an inorganic near-infrared ray absorbent is used, and providing an antireflection film. The disclosed near-infrared ray absorption hard coat film is constituted by forming a near-infrared ray absorption layer on a surface of a film base material. The near-infrared ray absorption layer is formed of the inorganic near infrared ray absorbent and a binder, and refractive index difference between the inorganic near infrared ray absorbent and a hardened object of the binder is set to 0.16 or less. Preferably the refractive index of the inorganic near infrared ray absorbent is 1.56 to 1.76 and the refractive index of the hardened object of the binder is 1.49 to 1.65. A low refractive index layer with the refractive index of 1.20 to 1.45 is formed on the near-infrared ray absorption layer of the near-infrared ray absorption hard coat film to obtain the antireflection film. CITATION LIST PATENT LITERATURE PATENT LITERATURE 1: JP-A-2015-118281PATENT LITERATURE 2: JP-A-2015-104865 SUMMARY OF INVENTION TECHNICAL PROBLEM An object of the present invention is to provide a laminated film in which an antireflection function and an infrared-shielding function are excellent, transparency is high, and reflection color irregularities (which are usually perceived as color difference like an oil film formed on water or gradation like rainbow by visual observation) are suppressed. SOLUTION TO PROBLEM As a result of diligent research, the present inventor has found that a laminated film having a specific structure could achieve the above object. The invention is defined in the independent claim. Further advantageous embodiments are defined in the dependent claims. ADVANTAGEOUS EFFECTS OF INVENTION In the laminated film of the present invention, an antireflection function and an infrared-shielding function are excellent, transparency is high, and reflection color irregularities are suppressed. Therefore, this laminated film can be suitably used for e.g. a building window glass, a car roof window, and a car front window. BRIEF DESCRIPTION OF DRAWINGS FIG 1 is a cross-sectional diagram which shows an example of the laminated film of the present invention.FIG 2 is a conceptual diagram of a film-forming device used in Examples.FIG 3 is a conceptual diagram which illustrates a difference in reflectance between the top of the waveform around a wavelength with the lowest reflectance and the bottom of the waveform adjacent thereto in a reflectance spectrum before smoothing treatment. DESCRIPTION OF EMBODIMENTS The term "film" is herein used as a term also i