Parchmentized fibrous support containing parchmentizable synthetic fibers and method of manufacturing the same
The present invention relates to a parchmentized fibrous support containing parchmentizable synthetic fibers parchmentized with sulfuric acid, the process for making such a support and the use thereof.
1. A process of making a parchmentized fibrous support comprising the steps of:
(a) forming a fibrous support comprised of parchmentizable synthetic aramid fibers and parchmentizable synthetic aramid fibrids; and
(b) parchmentizing the parchmentizable synthetic aramid fibers and fibrids of the fibrous support by treating the fibrous support with H 2 SO 4 at a concentration from about 50% to about 100% and at a temperature from about −20° C. to about +50° C. for between about 5 to about 60 seconds sufficient to obtain a parchmentized fibrous support having an increased strength of at least 30% as compared to the strength of the fibrous support formed according to step (a).
2. The process of claim 1 , wherein step (a) is practiced by hydroentangling the parchmentizable synthetic aramid fibers and parchmentizable synthetic aramid fibrids to form the fibrous support.
3. The process of claim 1 , comprising forming two fibrous supports and thereafter together parchmentizing the two fibrous supports.
4. The process of claim 1 , wherein step (b) is practiced by treating the fibrous support with H 2 SO 4 at a concentration of from 72% to 90% for between about 10 to about 20 seconds.
5. The process of claim 4 , wherein the fibrous support comprises about 60 wt. % of the parchmentizable synthetic aramid fibers and about 40 wt. % of the parchmentizable synthetic aramid fibrids.
6. The process of claim 1 , wherein step (a) comprises including in the fibrous support synthetic fibers selected from the group consisting of polyamide-based fibrous materials; polyester-based fibrous materials; carbon fibers; glass fibers; and mixtures thereof.
7. The process of claim 1 , wherein step (a) comprises including natural fibers in the fibrous support.
8. The process of claim 7 , wherein the natural fibers comprise cellulose fibers.
9. The process of claim 8 , wherein the cellulose fibers comprise regenerated cellulose fibers.
10. The process of claim 1 , wherein step (a) comprises including in the fibrous support at least one non-fibrous material selected from the group consisting of titanium dioxide, mica, talc, clay, and organic non-fibrous fillers.
11. The process of claim 1 , wherein the parchmentizable synthetic aramid fibers and the parchmentizable aramid fibrids comprise 100 wt. % of the fibrous support formed according to step (a).
12. The process of claim 1 , which further comprises the step of:
(e) calendering the parchmentized fibrous support.
13. The process of claim 12 , wherein step (e) comprises calendering the parchmentized fibrous support at a temperature from about 80° C. to about 350° C.
14. The process of claim 13 , wherein parchmentized fibrous support is calendered at a temperature from about 120° C. to about 320° C.