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...
Patent
1991-03-19
1993-12-07
Michl, Paul R.
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...
524565, 524582, 524585, 524586, 264 63, 264166, 2642905, C08L 2904, C08L 3320, C08L 2302, C04B 3564
Patent
active
052684156
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a thin self-supporting inorganic green compact which contains an inorganic substance and a binder and is less than 25 .mu.m thick.
Such inorganic green compacts are described in EP-A-0210874.
A drawback of the green compacts described in said patent, in this case films, is that cellulose is used as binder, which limits the stretchability of the green compacts. Because this means that the desired extremely thin films have to be produced in one go. The films are produced by first applying a thin layer of the solution containing binder and inorganic substance to a support, drying it and then separating the layer from the support. Such a process imposes very high intrinsic requirements on the equipment to be used to produce the films because irregularities in thickness or cracks easily occur. For the same reason such processes are extremely sensitive to the occurrence in the added inorganic substance of particles with dimensions similar to the layer thickness. In practice, it therefore appears to be hardly possible to produce very thin-walled objects without cracks in this manner, tests having shown that it is very difficult to remove the films from the support, in particular in the case of thin films (10-20.mu.). Moreover, cellulose is sensitive to moisture, as a result of which the dimensional stability is adversely affected, which precludes specific applications. In the framework of the invention reference is made to a green compact as long as the organic binder is still present as such and has not yet been removed or converted.
The aim of the invention is to provide thin green compacts of an inorganic substance bound with an organic binder which do not have the aforementioned drawbacks.
The green compacts according to the invention are characterized in that the binder consists substantially of a polymer with a weight average molecular weight of more than 400,000, which polymer, incorporated in a suitable solvent, forms a thermoreversible gelling system with gel and dissolution points above room temperature, the volume fraction of the inorganic substance being more than 45% relative to the total amount of binder and inorganic substance.
Such green compacts are easily obtainable without having to impose particularly high requirements on the equipment to be used. Moreover, it is possible to use said green compacts to apply inorganic layers, whether or not sintered, in objects. An example of such an object is a multilayer ceramic capacitor, in the case of which a low ceramic layer thickness is a great advantage with respect to the miniaturisation aimed at in this application.
The invention therefore also relates to a process for the preparation of said green compacts and the use of the green compacts according to the invention in the application in objects of layers containing inorganic substance.
DE-A-2334704 describes the preparation of fibres of polyethylene oxide in which substantial amounts of fillers can be incorporated. The polymer-solvent system described in said patent is a high-viscosity solution at room temperature, which causes problems with respect to the feeding of the extruder. Another drawback of the polyethylene oxide/water system used is that this system does not form a gelling system until it is cooled to below room temperature. At room temperature the product obtained therefore remains tacky as long as it contains solvent. Consequently, the solvent has to be removed to enable further processing. This is a particular drawback because the solvent has to be removed from the unstretched and thus thicker green compact, which is more difficult and takes longer.
Thermoreversible gelling systems are in the scope of the invention understood to be systems characterized by the fact that the conversion into a gel of a polymer dissolved in a solvent is effected by means of a (rapid) drop in temperature. Examples of thermoreversible gelling systems with gel and dissolution points above room temperature are: polyalkenes with the usual solvents such as paraffins, toluene, xylene, t
REFERENCES:
patent: 3189978 (1965-06-01), Stetson
patent: 3536508 (1970-10-01), Short
patent: 3988524 (1976-10-01), Dreyer et al.
patent: 4411854 (1983-10-01), Maurer et al.
patent: 4734237 (1988-03-01), Fanelli et al.
patent: 4752857 (1988-01-01), Khoury et al.
patent: 4765950 (1988-08-01), Johnson
patent: 4814370 (1989-03-01), Kramer et al.
patent: 4882110 (1989-11-01), Kramer et al.
patent: 4900698 (1990-02-01), Lundsager
patent: 4921652 (1990-01-01), Tsuji et al.
patent: 5064596 (1991-11-01), Chida et al.
patent: 5069839 (1991-12-01), Grote et al.
Bastiaansen Cornelis W. M.
Heffels Frans
Pieterse Jan K.
Pontenagel Willibrordus M. G. F.
Michl Paul R.
Stamicarbon B.V.
Szekely Peter
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