| abstract |
This invention concerns a light weight sheet felt material suitable for use as roof and siding underlayment and insulation board facing which comprises on a dry basis (a) 60-80 wt. % cellulose fibers; (b) 15-30 wt. % glass fibers having a diameter of 5 to 16 microns and a length of +E,fra 3/8+EE -+E,fra 3/4+EE inch; (c) 4-10 wt. % binder and (d) 0.5-10 wt. % non-asphaltic, sizing agent having a flash point above 150 DEG F. and an evaporation rate less than one which is selected from the group consisting of anionic rosinous and amphipathic ester and anhydride sizes and mixtures thereof. The felt of this invention is of considerably lighter weight and higher porosity than other felting materials used for the same purpose and can be supplied in longer continuous sheet rolls than heretofore practical from a standpoint of handling, shipping, storage, and installation. Also the present sheet felt can be produced on conventional felt making equipment in a one step process. |