Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1996-03-22
1999-01-12
Le, H. Thi
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428328, 428331, 428404, 428407, B32B 516
Patent
active
058585265
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a composite material having a high refractive index, its production process, as well as optically active materials such as antireflection and reflecting materials made from said composite material.
2. Description of the Prior Art
Antireflection and reflecting materials are formed by an organic or inorganic substrate, covered with several coatings, certain of which have sought, specific, optical properties. More specifically, interferential dielectric mirrors incorporating a substrate, covered with a dielectric film reflecting one or more desired wavelengths, whilst having a relatively low intrinsic absorption compared with the metals conventionally used for producing such mirrors. Antireflection or reflecting materials have numerous applications.
Thus, organic or inorganic substrates, i.e. in particular plastics or vitreous substrates, coated with an antireflection film have particular interest in the fields of ophthalmic and video products or architectural applications, such as glass panels placed on the outside of buildings. In addition, antireflection materials and interferential dielectric mirrors can also be used in high energy lasers, solar, thermal and photovoltaic applications or in integrated optical systems.
The prior art already discloses processes making it possible to produce antireflection materials or interferential dielectric mirrors and said processes are referred to hereinafter.
Thus, U.S. Pat. No. 2,466,119 discloses a process for the preparation of multilayer, reflecting and/or antireflection films, by hydrolysis and condensation of mixtures of titanium halides and/or silicon alkoxides. The porosity of said layers is controlled by varying the temperature. However, the obtaining of layers having a good mechanical strength requires heating to temperatures above those which can be withstood by conventional plastics, whose maximum thermal stability is 150.degree. C.
The NTIS U.S. patent application 7 148 458 corresponding to U.S. Pat. Nos. 4,929,278 and 4,699,812, describes a process for depositing antireflecton films on plastic substrates consisting of synthesizing an ethanol gel in the SiO.sub.2 --B.sub.2 O.sub.3 --Al.sub.2 O--BaO system until a certain molecular complexity is obtained, followed by the reliquefying of said gel by mechanically breaking certain interpolymer bridges. This gives a porous film with a low refractive index of approximately 1.23, produced at ambient temperature, which permits an adaptation to plastic substrates. However, this film only has a mediocre abrasion resistance.
U.S. Pat. Nos. 2,432,484 and 4,271,210 disclose the possibility of using silica or alumina colloids for producing antireflection dielectric coatings, making it possible to increase the porosity of said coatings and therefore lower their refractive indexes. However, the colloidal coatings obtained have a very poor mechanical strength and are particularly sensitive to any physical contact.
Moreover, although in the solar sector, plastics such as polycarbonates, polyacrylates, polyallyl carbonates, etc. are particularly interesting, vitreous substrates are also of interest, particularly in the field of general optics. However, it is clear that due to approximately 4% reflection losses for each air-glass interface encountered (the average index of glass being 1.5), the balance of losses for a complex optical system is often disadvantageous.
Therefore optical experts have long sought to create antireflection films by the use of physical processes such as vacuum deposition or evaporation. However, these processes are sophisticated and expensive, not generally being adapted to large scale, inexpensive production.
Finally, French patent application FR-A-2 680 583 of the CEA describes a material having antireflection properties, as well as abrasion resisting and hydrophobic properties. This material comprises an organic or inorganic substrate, successively covered by an adhesion promoting coating made from a material chosen fr
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Belleville Philippe
Floch Herve
Commissariat a l''Energie Atomique
Le H. Thi
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