Multilayered sheet
View Patent ↗This invention is directed to a multilayered sheet comprising a release paper and an inorganic refractory layer coated onto one surface of the release paper wherein the refractory layer has a dry areal weight of from 15 to 50 gsm and a residual moisture content of no greater than 10 percent by weight. The paper comprises a blend of cellulose and cotton fibers and is hydrophilic.
1. A multilayered sheet comprising a release paper having a first and a second outer surface and an inorganic refractory layer adjacent to at least one surface of the release paper wherein the inorganic refractory layer has a dry areal weight of from 15 to 50 gsm and a residual moisture content of no greater than 10 percent by weight, wherein the release paper
(i) comprises a blend of cellulose and cotton fibers,
(ii) is hydrophilic
(iii) has a wet tensile strength of at least 5 lb/in in a first direction and at least 2 lb/in in a second direction, the second direction being transverse to the first direction,
(iv) has a dry tensile strength of at least 10 lb/in in a first direction and at least 5 lb/in in a second direction, the second direction being transverse to the first direction,
(v) has a surface smoothness on at least one outer surface of no greater than 150 Sheffield units,
(vi) has a surface release value from at least one outer surface of from 0.25 to 1.5 lb/in,
(vii) has a thickness of from 5 to 12 mil,
(viii) has a density of from 0.9 to 1.1 g/cc, and
(ix) has an air permeability no greater than 1200 Gurley Air Resistance (sec/100cc, 20 oz. cyl.).
2. The multilayered sheet of claim 1 wherein the inorganic refractory layer comprises vermiculite.
3. The multilayered sheet of claim 2 wherein the inorganic refractory layer further comprises cations.
4. The multilayered sheet of claim 1 wherein the release paper further comprises up to 5 weight percent of a dimensional stability promoting additive.
5. The multilayered sheet of claim 4 wherein the dimensional stability promoting additive is micro-glass, fiberglass or polyethylene.
6. The multilayered sheet of claim 1 wherein the release paper is thermally stable at 150 deg C for at least 10 minutes.
7. The multilayered sheet of claim 1 wherein the refractory layer has a dry areal weight of from 20 to 35 gsm.
8. The multilayered sheet of claim 1 wherein the refractory layer has a residual moisture content of no greater than 3 percent by weight.
9. The multilayered sheet of claim 1 wherein the release paper has a dry tensile strength of from 60 to 90 lb/in in a first direction and from 20 to 40 lb/in in a second direction, the second direction being transverse to the first direction.
10. The multilayered sheet of claim 1 wherein the release paper has a surface smoothness on at least one outer surface of from 60 to 80 Sheffield units.
11. The multilayered sheet of claim 1 wherein the release paper has a thickness of from 9 to 11 mil.
12. The multilayered sheet of claim 1 wherein the release paper has an air permeability of 300 to 700 Gurley Air Resistance (sec/100cc, 20 oz. cyl.).