Appeal 2007-2181
Application 10/261,862
[3] Nakaishi is silent as to the use of any specific type of aramid paper
and any temperature differential between calendering rolls.
2. Yamamoto
[4] Yamamoto describes a composite aramid paper comprising (a) a high
density layer comprising aramid fiber alone and (b) an air permeable,
highly porous layer comprising a mixture of aramid fiber and a heat-
resistant organic fiber, wherein the composite aramid paper is said to
have heat resistance and electrical insulating properties superior to
single layer aramid papers (¶¶ 1, 7, 9).
[5] According to Yamamoto, when porosity is too low, processability and
impregnation, e.g., with resin, is less efficient (¶ 11).
[6] The composite paper is produced by (a) forming aramid fiber alone
into a wet paper, (b) forming a mixture of aramid fiber and a heat-
resistant organic fiber into a wet paper, (c) laminating the two wet
papers into a single composite wet paper, (d) drying, (e) preheating at
a temperature of 250o - 380o C, and (f) thermally compressing the
composite paper using a calender roll at a temperature lower than the
preheating temperature and in the range of 200o to 300o C (¶¶ 12, 19).
[7] According to Yamamoto,
[a]s for the temperature condition used for the
aforementioned calender treatment, it is desirable
when the temperature at the surface of the roll that
comes in contact with the layer comprising m-
aramid fibrid alone [i.e., the high density layer] is
reduced at least 20oC below the temperature of the
surface of the roll that comes in contact with the
mixed m-aramid fibrid and heat-resistant organic
fiber layer [i.e., the highly porous layer] and in
some cases, it is further desirable when the
aforementioned calender temperature condition is
6
Page: Previous 1 2 3 4 5 6 7 8 9 Next
Last modified: September 9, 2013