Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2003-01-16
2004-04-20
Choi, Ling-Siu (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C526S314000, C526S262000, C526S329700, C526S316000, C526S279000
Reexamination Certificate
active
06723770
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing an organic-inorganic composite material formed from an organic polymer and a metal alkoxide, an organic-inorganic composite material obtained by this method, and a laminate thereof.
2. Related Art
Inorganic materials such as metal and ceramics are excellent in heat resistance, mechanical strength, electrical properties, optical properties, chemical stability etc., and used widely in industry by utilizing these properties. However, these materials are generally highly brittle and rigid, and their use may be limited because work or mechanical processing at a high temperature is necessary for working them into a desired shape.
On the other hand, organic polymers are excellent in workability and have flexibility, so that they can be easily worked into a desired shape. However, the organic polymers are often inferior to the inorganic materials in heat resistance and chemical stability.
Hence, attention is attracted in recent years to an organic-inorganic composite material comprising an inorganic material and an organic polymer material to attain the properties of the two.
As the composite material of an organic polymer and an inorganic material, a composite material having an inorganic material in a fibrous or powdery form dispersed in an organic polymer material has been used in various fields. In recent years, there is extensive development of an organic-inorganic nano-composite material (also called an organic-inorganic hybrid material) in which organic and inorganic regions are compounded at the nanometer level or molecular level.
Because the organic and inorganic regions can be dispersed at the nanometer level or molecular level, the organic-inorganic nano-composite material is used as a material for electronic components or as a material for mechanical components. Further, the organic or inorganic region in the material can be designed to be smaller than light wavelength, thus making light absorption and scattering low. Accordingly, the organic-inorganic nano-composite material has been studied to be used as a material for optical waveguide, optical fiber, or the like by providing optical transparency.
Methods of producing organic-inorganic composite materials are disclosed in “Structure of poly(vinylpyrrolidone)—silica hybrid”, Motoyuki Toki, et al., Polymer Bulletin 29, 653-660 (1992) and in “Organic-inorganic hybrid sol-gel materials, 1”, Jen Ming Yang, et al., Die Angewandte Makromolekulare Chemi 251 (1997) 49-60 (Nr. 4356) etc.
However, the production methods described in these literatures have a problem that organic-inorganic composite materials excellent in optical transparency cannot be obtained.
When the organic-inorganic nano-composite material is used as an optical waveguide, its light transmission layer is often formed on a substrate. In this case, the adhesion of the substrate to the light transmission layer is important.
For the purpose of improving the adhesion, it has been attempted to provide a graded structure with the material by continuously changing its composition.
For example, in Japanese Patent Laid-Open No. 34413(2000), proposed is a silica/polycarbonate-based composite material wherein the concentration of silica is continuously changed by applying successively a plurality of coating solutions different in the composition of organic and inorganic components on a substrate.
Further, in Japanese Patent Laid-Open No. 336281(2000), proposed is a graded structure prepared by applying a coating solution consisting of a mixture of an organic polymer and a metal compound capable of forming a metal oxide by hydrolysis on an organic substrate, then heating and drying it, the graded structure having a higher content of the organic component at the side of the substrate and a higher content of the inorganic component in the vicinity of the surface.
However, the methods proposed in the publications described above have a problem that the adhesion of the light transmission layer to the substrate cannot be sufficiently improved.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a production method capable of producing an organic-inorganic composite material excellent in optical transparency, as well as an organic-inorganic composite material obtainable by this method.
A second object of the present invention is to provide a light transmission structure having a light transmission layer with improved adhesion to a substrate.
The production method of the present invention is a method of producing an organic-inorganic composite material formed from an organic polymer and a metal alkoxide, which comprises the steps of polycondensating a metal alkoxide through hydrolysis until the unreacted metal alkoxide is reduced to 3 vol. % or less, and mixing the polycondensated metal alkoxide with an organic polymer to form an organic-inorganic composite material.
In the present invention, a metal alkoxide is polycondensated through hydrolysis until the unreacted metal alkoxide is reduced to 3 vol. % or less, and the polycondensated metal alkoxide is mixed with an organic polymer to form an organic-inorganic composite material. The obtained organic-inorganic composite material is excellent in optical transparency. Thus, according to the present invention, an organic-inorganic composite material suitable as a material for optical component such as optical waveguide or optical fiber can be produced.
The metal alkoxide used in the present invention includes alkoxides of metals such as Si, Ti, Zr, Al, Sn and Zn. In particular, Si, Ti or Zr alkoxide is preferably used. Accordingly, alkoxy silane, titanium alkoxide and zirconium alkoxide are preferably used, and particularly alkoxy silane is preferably used. The alkoxy silane includes tetraethoxy silane, tetramethoxy silane, tetra-n-propoxy silane, tetraisopropoxy silane, tetra-n-butoxy silane, tetraisobutoxy silane, phenyltriethoxy silane, phenyltrimethoxy silane, 3-methacryloxypropyltriethoxy silane, and 3-methacryloxypropyltrimethoxy silane.
The organic polymer in the present invention is not particularly limited insofar as it forms an organic-inorganic composite material with a metal alkoxide. The organic polymer includes, for example, polyvinylpyrrolidone, polycarbonate, polymethylmethacrylate, polyamides, polyimides, polystyrene, polyethylene, polypropylene, epoxy resins, phenol resins, acryl resins, urea resins, melamine resins etc. From the viewpoint of formation of the organic-inorganic composite material excellent in optical transparency, polyvinylpyrrolidone, polycarbonate, polymethylmethacrylate, polystyrene or a mixture thereof is used preferably as the organic polymer.
Hydrolysis of the metal alkoxide is conducted preferably in the presence of water for hydrolysis and an acid as a catalyst for hydrolysis. The molar ratio of water for hydrolysis to the metal alkoxide (water/metal alkoxide ratio) is preferably from 1.0 to 3.0, more preferably from 1.5 to 2.5. The acid used as a catalyst for hydrolysis includes inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, as well as organic acids, and particularly hydrochloric acid is preferably used. The molar ratio of hydrochloric acid to the metal alkoxide (hydrochloric acid/metal alkoxide ratio) is preferably from 0.001 to 0.5, more preferably from 0.001 to 0.01, particularly preferably 0.002.
The amount of the unreacted metal alkoxide, that is, the amount of the remaining metal alkoxide, can be measured by gas chromatography etc. The reaction time in which the amount of the remaining metal alkoxide is reduced to 3 vol. % or less is previously determined by hydrolyzing the metal alkoxide under predetermined conditions of temperature, concentration etc., and for the determined reaction time, the metal alkoxide is hydrolyzed and polycondensated, and then mixed with an organic polymer to form an organic-inorganic composite material. Alternatively, the amount of the unreacted metal alkoxide may be measured every time the compo
Hirano Hitoshi
Izu Hiroaki
Kuramoto Keiichi
Yamano Koji
Choi Ling-Siu
Fasse W. F.
Fasse W. G.
Sanyo Electric Co,. Ltd.
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