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EP-3951446-B1 - LOW REFLECTIVE FILM AND OPTICAL SENSING KIT USING THE SAME, AND LOW REFLECTIVE MOLDED PRODUCT

EP3951446B1EP 3951446 B1EP3951446 B1EP 3951446B1EP-3951446-B1

Inventors

  • NOZAWA, KAZUHIRO
  • NAGAHAMA, Tsuyoshi
  • TOMIZAWA, SHUZO

Dates

Publication Date
20260506
Application Date
20200306

Claims (15)

  1. A low reflective film (100, 200, 300, 400) comprising at least a first resin layer (21), wherein the first resin layer (21) comprises at least a binder resin (22), and an organic resin particle (23) having an average particle size D 50 of 2 to 20 µm which is a median size on a volume basis, measured by laser diffraction type particle size distribution measurement, and a surface of the first resin layer (21) has gloss values satisfying the following relationship, specular gloss values being measured in accordance with JIS-Z8741:1997: specular gloss value at 60 degrees: 0.0% or more and 6.0% or less, and specular gloss value at 85 degrees: 0.0% or more and 6.0% or less, characterised in that the surface of the first resin layer (21) has a surface roughness Ra of 0.8 to 4.0 µm, measured in accordance with JIS-B0601:2001, and has a reflectance and gloss values satisfying the following further relationships: (1) regular reflectance at 70 degrees: 0.0% or more and 2.5% or less (wavelength 550 nm), (2) specular gloss value at 75 degrees: 0.0% or more and 6.0% or less, and (3) a sum of a specular gloss value at 20 degrees, a specular gloss value at 45 degrees, the specular gloss value at 60 degrees, the specular gloss value at 75 degrees, and the specular gloss value at 85 degrees is 7.5% or less.
  2. The low reflective film according to claim 1, wherein the organic resin particle (23) has an average particle size D 50 of 5 to 20 µm.
  3. The low reflective film according to claim 1 or 2, wherein a content rate of the organic resin particle (23) to the binder resin (22) is 0.6 to 2.5.
  4. The low reflective film according to any one of claims 1 to 3, wherein the first resin layer (21) has a thickness T of 0.5 to 8.0 times of an average particle size D 50 of the organic resin particle (23) comprised in the first resin layer (21).
  5. The low reflective film according to any one of claims 1 to 4, having an optical density of 0.5 or more.
  6. The low reflective film according to any one of claims 1 to 5, wherein the first resin layer (21) further comprises carbon black.
  7. The low reflective film according to any one of claims 1 to 6, having a laminated structure comprising at least the first resin layer (21) and a pressure-sensitive adhesive layer (31) in the listed order.
  8. The low reflective film according to any one of claims 1 to 7, having a laminated structure comprising at least the first resin layer (21) and a substrate film (11) in the listed order.
  9. The low reflective film according to any one of claims 1 to 8, having a laminated structure comprising at least the first resin layer (21), a substrate film (11), and a pressure-sensitive adhesive layer (31) in the listed order.
  10. The low reflective film according to any one of claims 1 to 9, having a laminated structure comprising at least the first resin layer (21), a substrate film (11), a second resin layer (41), and a pressure-sensitive adhesive layer (31) in the listed order.
  11. The low reflective film according to any one of claims 7 to 10, wherein the pressure-sensitive adhesive layer (31) comprises one or more pressure-sensitive adhesives selected from the group consisting of a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, an olefin-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive.
  12. An optical sensing kit comprising at least an optical sensor which is disposed in an inside of a room of a moving vehicle and which images an outside of the room of the moving vehicle or detects visible light or infrared light in the outside of the room through a window transparent to visible light or infrared light, and a low reflective film which covers a surface of an interior part disposed in the inside of the room and which reduces reflected light of external light on the surface to thereby allow the optical sensor to be enhanced in imaging accuracy and/or detection accuracy, wherein the low reflective film is a low reflective film (100, 200, 300, 400) in accordance with claim 1.
  13. The optical sensing kit according to claim 12, wherein the organic resin particle (23) has an average particle size D 50 of 5 to 20 µm.
  14. The optical sensing kit according to claim 12 or 13, wherein the interior part corresponds to one or more selected from the group consisting of a resin molded product, a multi-layered laminated product using the resin molded product, a non-woven fabric, and a skin material.
  15. A low reflective molded product wherein the low reflective molded product comprises at least a binder resin (22), and an organic resin particle (23) having an average particle size D 50 of 2 to 20 µm which is a median size on a volume basis, measured by laser diffraction type particle size distribution measurement, and at least one surface of the low reflective molded product has a surface roughness Ra of 0.8 to 4.0 µm, measured in accordance with JIS-B0601:2001, and has a reflectance and gloss values satisfying the following relationships, specular gloss values being measured in accordance with JIS-Z8741:1997: (1) regular reflectance at 70 degrees: 0.0% or more and 2.5% or less (wavelength 550 nm), (2) specular gloss value at 60 degrees: 0.0% or more and 6.0% or less, specular gloss value at 75 degrees: 0.0% or more and 6.0% or less, specular gloss value at 85 degrees: 0.0% or more and 6.0% or less, and (3) a sum of a specular gloss value at 20 degrees, a specular gloss value at 45 degrees, the specular gloss value at 60 degrees, the specular gloss value at 75 degrees, and the specular gloss value at 85 degrees is 7.5% or less.

Description

[Technical Field] The present invention relates to a novel low reflective film low in surface reflectance and surface gloss value at a wide angle, and an optical sensing kit using the low reflective film, as well as a low reflective molded product and the like. [Background Art] According to recent remarkable progress in a sensing technology, there has been studied introduction of a high-level sensing technology into various moving bodies (hereinafter, sometimes referred to as "moving vehicles".) such as automobiles, railway trains, trains, electric trains, ships, cargo ships, aircrafts, spacecrafts, rockets, transport equipment, and vehicles. As one example, an automobile has been progressively developed where an optical sensor provided with an imaging element, such as a camera module or an infrared sensor, is placed in an inside of the automobile in order to detect any obstacle (for example, other vehicle, a pedestrian, a guardrail, and a house) located in front of own vehicle. Such an optical sensor, for example, images a vehicle outside from a vehicle inside through window glass, or detects visible light and/or infrared light in a vehicle outside from a vehicle inside. Meanwhile, a large number of interior members such as a dashboard, a roof trim, a sun visor, a switch panel, a decoration panel, steering, and a seat are placed in the inside of a moving vehicle in which such an optical sensor is placed, and such an optical sensor may also be provided with resin accessories such as a camera hood and a lens hood (hereinafter, these are sometimes collectively referred to as "interior part"). In such an interior part, a molded product with light weight and excellent durability made of a resin such as a thermoplastic resin and a thermoplastic elastomer, a multi-layered laminated product using such a resin, a non-woven fabric or a skin material and the like have been recently used frequently. For such interior parts for moving vehicles, there have also been proposed a large number of resin materials suppressing gloss of a product surface and imparting matting properties (see Patent Literatures 1 to 4) from the viewpoint of safety or from the viewpoint of designability for providing a mat-toned and gentle texture imparting a high-class feeling. [Citation List] [Patent Literature] [Patent Literature 1] Japanese Patent Laid-Open No. 6-057007[Patent Literature 2] Japanese Patent Laid-Open No. 7-314519[Patent Literature 3] Japanese Patent Laid-Open No. 2002-220562[Patent Literature 4] Japanese Patent Laid-Open No. 2003-020384Further, US 2014/0016202 A1 discloses a light shielding material with properties from which the pre-characterising part of claim 1 starts out. [Summary of Invention] [Technical Problem] A sensing technology using the above-mentioned optical sensor causes halation, lens flare, ghost, and/or the like to occur to result in remarkable degradation of an image taken or remarkable deterioration in detection accuracy of sensing, when light (unnecessary light) reflected on the surface of any interior part is incident into such an optical sensor. On the contrary, the techniques of Patent Literatures 1 to 4 are each merely a technique for imparting matting properties in terms of an appearance, and still exhibit large surface gloss values (a specular gloss value at 60 degrees of 9 to 35% (Patent Literature 1), a specular gloss value at 60 degrees of 10 to 30% (Patent Literature 2), a specular gloss value at 60 degrees of 7.3 to 15.2% (Patent Literature 3), and a specular gloss value at 45 degrees of 4.7 to 18% (Patent Literature 4)). Thus, there is a demand for development of a material smaller in surface gloss value. In particular, imaging, sensing, and the like tend to be hereafter demanded at extremely high accuracies in an application of an optical sensing kit for moving vehicles. A resin material low in gloss, for use in such an application, usually exhibits a relatively large specular gloss value at a wide angle (both an incident angle and a reflection angle: 45° or more) as compared with a specular gloss value at a low angle (both an incident angle and a reflection angle: less than 45°). Thus, such a resin material low in gloss, of Patent Literatures 1 to 4, not only exhibits large specular gloss value at 45 degrees and specular gloss value at 60 degrees, but also exhibits a larger specular gloss value at a much wider angle, for example, a larger specular gloss value at 75 degrees and a larger specular gloss value at 85 degrees. For example, a light-shielding film (product name: Carbonfeather X6B manufactured by KIMOTO) as a commercially available product exhibits a surface reflectance and surface gloss values, as follows. Accordingly, in a case where such a resin material of the prior art is used in an application of an optical sensing kit, the influence of reflected light at a wide angle still highly remains and thus imaging, sensing, and the like are difficult to perform at higher accuracies. [Tab