Paper making and fiber liberation – Processes and products – Mineral fiber
Reexamination Certificate
1999-08-31
2001-07-10
Fortuna, Jose (Department: 1731)
Paper making and fiber liberation
Processes and products
Mineral fiber
C162S149000, C162S156000, C162S169000
Reexamination Certificate
active
06258211
ABSTRACT:
BACKGROUND
The invention concerns a process for producing high temperature-resistant technical paper, in which fibers serving as reinforcing elements are mixed with a wet paper material pulp and then technical paper is produced from the pulp by the removal of water from the pulp and resulting compacting of the paper material. In addition the invention concerns a high temperature-resistant technical paper which is produced in particular in accordance with that process.
High temperature-resistant technical papers are produced for example in thicknesses or sizes of between 0.5 and 5 mm. The production of high temperature-resistant technical papers is similar to the production of conventional papers, that is to say the technical papers, like other papers, are produced from a wet paper material pulp by the removal of water from the pulp and compacting which occurs as a result of the fibrous paper material.
It is known to produce high temperature-resistant papers for technical purposes, which contain ceramic fibers as reinforcing means. Ceramic papers of that kind which are used for thermal insulation purposes at up to 1,000° C. however suffer from the disadvantage that under operating conditions they suffer from comparatively severe shrinkage, more specifically for example between 2 and 4%. In addition those known ceramic papers involve the problem that the ceramic fibers which are used for same are not of a defined diameter but the diameter is generally below 3 &mgr;m so that the fibers of those ceramic papers can pass into the lungs and are considered to be a cause for concern in regard to health.
The object of the present invention is to provide a high temperature-resistant technical paper which can be used for example for thermal insulating purposes and which enjoys improved stability in respect of shape so that it does not experience unfavorable changes in practical operation and in particular its configuration and dimensions do not undesirably alter.
SUMMARY OF THE INVENTION
Briefly, according to this invention, there is provided a process for producing high temperature-resistant technical paper, in which fibers are mixed with a wet paper material pulp and then technical paper is produced from the pulp by the removal of water from the pulp and resulting compacting of the paper material, characterised in that the fibers added to the wet pulp are fibers which have been cut and previously thermally shrunk. Preferably, the fibers added to the wet pulp are cut, thermally shrunk silica fibers which are mixed with the wet pulp prior to production of the technical paper. Preferably, the silica fibers comprise between 80 and 99.98% of SiO
2
. Preferably, the technical papers have a density or weight in relation to surface area of between 10 and about 400 g/m
2
are produced.
Briefly, according to this invention, there is provided a high temperature-resistant technical paper characterised in that the paper contains thermally shrinkable fibers such as silica fibers which are thermally pre-shrunk prior to production of the paper. Preferably, the paper is between 0.5 and 5 mm in thickness. Preferably, the paper comprises silica fibers of a mean diameter of 6 &mgr;m and is produced in a wet process with organic binding agents, for example, an acrylate.
REFERENCES:
patent: 3300372 (1967-01-01), Bauer
patent: 3682667 (1972-08-01), Roberts et al.
patent: 3687850 (1972-08-01), Gagin
patent: 5041321 (1991-08-01), Bendig
patent: 5053107 (1991-10-01), Barber, Jr.
patent: 5273821 (1993-12-01), Olson et al.
Patent Abstracts of Japan, vol. 007, No. 085 (M-206), Apr. 8, 1983, JP 58 011397 A, Kanai Takeshi, entitled “Total Heat Exchange Element”.
Culimeta-Alfons Cuylits-Gesellschaft für Textilglas Technologie
Fortuna Jose
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
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