Stock material or miscellaneous articles – Composite – Of fluorinated addition polymer from unsaturated monomers
Patent
1994-04-25
1995-12-19
Nakarani, D. S.
Stock material or miscellaneous articles
Composite
Of fluorinated addition polymer from unsaturated monomers
427164, 427165, 427167, 427169, 427240, 4274071, 4274072, 428422, 428428, 428429, 428447, 428448, 428451, G02B 110, C03C 1734, C03C 1742
Patent
active
054767172
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a material having antireflection, hydrophobic and abrasion resistance properties. The invention also relates to a process for depositing an antireflection, hydrophobic and abrasion resistant deposit on an organic or inorganic substrate.
2. Discussion of the Background
Organic or inorganic substrates, i.e. in particular plastics or vitreous substrates, coated with an antireflection film have numerous applications. Substrates prepared in this way are of particular interest in the following fields: high power lasers, solar, thermal and photovoltaic applications, integrated optical systems or in architectural applications, such as external vitreous panels. In connection with solar applications, plastic or vitreous substrates are used in optical systems for minimizing heat losses, for concentrating and focussing light energy and finally for protecting certain absorbent elements. Compared with vitreous substrates, plastic substrates are less expensive, more easily modelled, lighter and less fragile in the case of shocks.
Numerous practical solutions have been proposed for the deposition of thin antireflection layers on substrates, but very few of them are appropriate for the treatment of plastics materials.
GB 1 444 152, GB 1 530 833 and U.S. Pat. No. 3,996,067 describe conventional methods for the deposition of antireflection layers on various plastics, namely vacuum evaporation, reactive plasma and fluorination processes. However, these procedures have never undergone significant industrial development, because they are onerous, lead to local overheating and therefore deformations and consequently only permit coating to take place on one face at once.
Most of the proposed solutions require the heating of the antireflection film at temperatures of around a few hundred degrees and sometimes at between 1000.degree. and 1400.degree. C. (cf. particularly U.S. Pat. No. 4,286,024), which are well above those which can be withstood by a plastics material (max thermal stability 150.degree. C.).
U.S. Pat. No. 2,466,119 discloses a process for the preparation of reflecting films and/or antireflection multilayer products by hydrolysis and condensation of mixtures of titanium halides and/or silicon alkoxides. The porosity of these coatings is checked by varying the temperature. However, once again the obtaining of coatings having a good mechanical strength requires heating to temperatures well above those which can be withstood by conventional plastic.
U.S. Pat. No. 4,361,598 describes a process for the sol-gel deposition of a dense antireflection film based on SiO.sub.2 /TiO.sub.2 on stainless steel or silicon cells. In order to convert the polymer into dense oxide, it is necessary to perform a heat treatment at between 300.degree. and 600.degree. C. Therefore this process cannot be applied to plastics materials. Moreover, the refractive index range covered by this patent varies between 1.4 and 2.4, whereas for obtaining a monolayer antireflection coating on a plastic substrate, it is necessary to have a refractive index of approximately 1.22.
U.S. Pat. No. 4,397,666 describes a process for the deposition of a thick sol-gel film containing several components by acting on the viscosity by adding an agent increasing the latter. The thickness of the film obtained varies between 0.3 and 1.0 micron and these thicknesses are much too great compared with the thickness of 0.123 micron specified by Fresnel equations, when it is wished to make a monolayer antireflection deposit on a plastics material.
U.S. patent application Ser. No. 7,148,458 (NTIS) (corresponding to U.S. Pat. Nos. 4,929,278 and 4,966,812) describes a process for depositing antireflection 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.sub.3 -BaO system until a certain molecular complexity is obtained, followed by the reliquefying of the said gel mechanically breaking certain interpolymer bridges. This leads to a porou
REFERENCES:
patent: 4929278 (1990-05-01), Ashley et al.
Commissariat a l''Energie Atomique
Nakarani D. S.
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