Patent ID: 6230901
Filing Date: 2001-05-15
Classification: B01D,D04H,Y10S

Abstract:
A process for producing a cylindrical filter consisting of high melting point thermoplastic resin microfine fibers and low melting point thermoplastic resin microfine fibers and having said high melting point thermoplastic resin microfine fibers fixed by melt-adhesion of said low melting point thermoplastic resin microfine fibers thereunto, which process comprises a step of spinning a high melting point thermoplastic resin and a low melting point thermoplastic resin, having a melting point difference of 10.degree. C. or more, according to a melt-blown spinning process, using the respective extruders therefor, through separate spinning nozzles in the same spinneret to form a combination of high melting point thermoplastic resin microfine fibers and low melting point thermoplastic resin microfine fibers wherein said high melting point thermoplastic resin microfine fibers and said low melting point thermoplastic resin microfine fibers are uniformly mixed in substance, while controlling the quantity of the low melting point thermoplastic resin extruded so as to give 10 to 90% by weight based upon the total extruded quantity of thermoplastic resins, to obtain a thermoplastic resin microfine mixed fiber web, a step of heating the thermoplastic resin microfine fiber web at a temperature between the melting temperature of the low melting point thermoplastic resin microfine fibers and that of the high melting point thermoplastic resin microfine fibers to bond the high melting point thermoplastic resin microfine fibers together, and a step of winding up the thermoplastic resin microfine mixed fiber web into a cylindrical form.