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
1999-08-18
2001-08-07
Cain, Edward J. (Department: 1714)
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...
C524S430000, C524S431000, C524S432000, C524S433000, C524S492000, C524S493000
Reexamination Certificate
active
06271292
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to mixtures for the production of organic-inorganic hybrid materials and to the use thereof.
By synthesising organic-inorganic hybrid materials, attempts are made to combine properties which are typical of inorganic and organic substances in one material. Thus, as is known, glass and ceramics are characterised by their hardness and brittleness, whereas organic polymers are flexible but at the same time are also considerably softer than the aforementioned substances. Meanwhile, very many organic-inorganic hybrid materials have become known which are considerably harder than organic polymers are but which nevertheless do not exhibit the brittleness of purely inorganic materials.
Hybrid materials are classified into different types depending on the type of interaction between the inorganic and the organic component. A review on this topic is given in J. Mater. Chem. 6 (1996) 511.
One class of hybrid materials is obtained by the reaction of a homogeneous mixture of an organic polymer with metal alkoxides, e.g. Si(OEt)
4
or CH
3
-Si(OEt)
3
, with water. After hydrolysis and condensation of the alkoxides, an inorganic network is obtained which is penetrated by the organic polymer (“interpenetrating network”). There is no covalent chemical bonding of the polymer to the inorganic phase. Examples of hybrid materials such as these are given in U.S. Pat. No. 5,346,939 and WO 93/01226.
According to Poly. Mater. Sci. Eng. 74 (1996) 65, the compatibility of the inorganic phase with strongly polar polymers such as polyamides, polyimides, polyamide-imides or polycarbonates is particularly good. With polymers which are less polar, however, e.g. polyvinyl chlorides or polymethyl methacrylates, which are extraordinarily important in industry, phase separation often occurs, i.e. heterogeneous, turbid materials are formed. The addition of polyoxazolines has been proposed in order to improve the compatibility in systems such as these.
Another class of materials is produced similarly, but contains reactive groups, e.g. Si(OEt)
3
groups, in the organic polymer which is used, which reactive groups effect covalent chemical bonding to the inorganic network. Examples thereof are given in ACS Symp. Ser. 585 (1995)125, Adv. Mater. 6 (1994) 372 and in Mater. Lett. 13 (1992) 261.
“Polymeric composites” which consist of an organic polymer and of an inorganic, glassy polymer are described in WO 93/01226. It is stated to be a characteristic of these materials that the organic polymer cannot be extracted and that no glass transition point or melting point is observed.
Mixtures consisting of unreactive, thermoplastic polymers with liquid organometallic compounds are known from U.S. Pat. No. 5,346,939. In the presence of water, composite materials are obtained therefrom in which there is no mixing at a molecular level, but in which the organic and inorganic phases are separate. Composite materials such as these are turbid, and are therefore unsuitable for applications for which highly transparent materials are required, for example covering lacquers.
SUMMARY OF THE INVENTION
The present invention therefore relates to mixtures consisting of:
A) at least one organic polymer,
B) inorganic particles,
C) at least one inorganic-organic binder,
D) solvent.
DETAILED DESCRIPTION OF THE INVENTION
Organic polymers A) in the sense of the invention may be polymers which are reactive or unreactive towards constituents B) and C).
Unreactive organic polymers do not form stable covalent bonds with the inorganic particles or with the inorganic-organic binder. The formation of Si—O—C bonds by the reaction of OH groups of the polymer with alkoxy groups, for example those of the organic-inorganic binder, is not seen in the sense of the present invention as the formation of a stable covalent bond, since a Si—O—C bond can be cleaved again with water under mild conditions. The “bonding” of the organic polymer to the inorganic components B) and C) in the latter case is essentially due to weak interactions. e.g. hydrogen bonds.
Reactive organic polymers in the sense of the invention contain groups which form stable covalent bonds, essentially Si—O—Si bonds or Si—O—Al bonds also, with the inorganic constituents B) and C). Organic polymers comprising corresponding reactive groups can be produced by (co-)polymerisation, as described in ACS Symp. Ser. 585 (1995) 125, Adv. Mater. 6 (1994) 372 and Mater. Lett. 13 (1992) 261, or by the functionalisation of an unreactive polymer. Substances which are suitable for this purpose exhibit a high level of reactivity towards the organic polymer and at the same time can also readily be bonded to the inorganic matrix. Examples include bifunctional organosilanes, which are already widely used as “coupling agents”, e.g. for the embedding of glass fibres in polymers. In particular, the following organosilanes can be cited as examples, wherein R=alkyl or aryl, preferably methyl or ethyl:
a) H
2
N—(CH
2
)
3
Si(OR)
3
b) H
2
N—(CH
2
)
2
—HN—(CH
2
)
3
Si(OR)
3
c) H
2
N—(CH
2
)
2
—HN—(CH
2
)
3
Si(OR)
2
(CH
3
)
d) C
6
H
5
—HN—(CH
2
)
3
Si(OR)
3
e) H
2
N—(CH
2
)
2
—HN—(CH
2
)
2
—HN—(CH
2
)
3
Si(OR)
3
f) OCN—(CH
2
)
3
Si(OR)
3
g) HS—(CH
2
)
3
Si(OR)
3
h) H
2
COCH—CH
2
—O
13
(CH
2
)
3
Si(OR)
3
i) H
2
C═C(CH
3
)—COO—(CH
2
)
3
Si(OR)
3
j) H
2
C═CH—Si(OR)
3
.
The aforementioned bifunctional organosilanes can be reacted with organic polymers in a manner which is schematically represented as follows:
It is also possible however, firstly to react the inorganic components B) and/or C), optionally with the bifunctional organosilanes, essentially with the formation of Si—O—Si bonds, and to effect reaction with the organic polymer thereafter.
Examples of organic polymers A) include polyimides, polycarbonates, polyesters, polyamides, polyketones, polyethers, polystyrenes, polyacrylonitriles, polyacrylamides, polymethacrylate esters, polyacrylate esters, polyvinyl esters, polyvinyl ethers and polyolefines, as well as copolymers and mixtures thereof (“blends”).
Commercially available polyol polymers are preferably used, e.g. those based on polyesters, polyacrylic esters or polymethacrylic esters, and polymers which contain isocyanates. Examples thereof include polyols based on polyacrylates or linear and branched polyesters or polyesters/polyethers.
If a plurality of organic polymers A) is used, these can also be reacted with each other, for example by the addition of polyol polymers to polymers which contain isocyanate groups.
Inorganic particles B) in the sense of the invention are oxides or hydrated oxides of metals, semimetals or non-metals which have a primary particle diameter of 1 to 100 nm, preferably 5 to 50 nm. This is a range within which the scattering of visible light (about 400 to 700 nm) is negligibly low, and highly transparent materials can thus be obtained. Examples of inorganic particles according to the invention include silica sols (SiO
2
), boehmite sols (Al(O)OH) and/or TiO
2
sols. Silica sols in organic solvents are preferred, since they can readily be mixed with other solvents, e.g. those which contain organic polymer A). However, in order to increase the solids content of the mixture according to the invention it is also possible to disperse inorganic particles B) in the organic polymer without the use of additional solvent (solvents which are necessary for dissolving the organic polymer are not “additional solvents” in the sense of the invention). Dispersions of SiO
2
particles in polar organic polymers, e.g. in polymers which contain OH groups, are preferably used. Dispersions in polyols, which are usually reacted with organic polymers which contain isocyanates, are most preferably used.
Organic-inorganic binders C) in the sense of the invention are polyfunctional organosilanes which contain at least 2, preferably at least 3 silicon atoms which each comprise 1 to 3 alkoxy or hydroxy groups, wherein the silicon atoms are each bonded by at least one Si—C bond to a structural unit which links the silicon atoms.
Example
Kraus Harald
Mager Michael
Puppe Lothar
Bayer Aktiengesellschaft
Cain Edward J.
Gil Joseph C.
Roy Thomas W.
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