| abstract |
A cylindrical filter which is easily produced and has a high withstand strength, a high filtration accuracy and a long filtration life; a microfine fiber web and a non-woven fabric suitable to a production of such a cylindrical filter; and processes for producing such web, non-woven fabric and cylindrical filter, are provided, n the web consisting of microfine mixed fibers spun according to melt-blown process, the mixed fibers consisting of high melting point microfine fibers and low melting point microfine fibers having a melting temperature difference of 10° c. or more, the low melting point microfine fibers being contained in a quantity of 10 to 90% by weight in the mixed fibers; the non-woven fabric being obtained by heat-treating the web; and the cylindrical filter being obtained by winding up the web or the nonwoven fabric, followed by heat-treatment. |