Patent Publication Number: US-2007096372-A1

Title: Method of manufacturing melt blown carbon fiber filter element and apparatus used therein

Description:
FIELD OF THE INVENTION  
      The invention is related to activated carbon fiber filter elements, method for manufacturing melt blown style of activated carbon fiber filter cartridges, and method for manufacturing activated carbon fiber filter cloth.  
     BACKGROUND OF THE INVENTION  
      As the major component of filtration system, the quality of the activated carbon fiber filter cartridge directly affects not only reliability of the filtration system, operating cost, but also working performance, safety and service life of the filtration system.  
      In the filter industry today, most of the existing activated carbon filter cloths are made of gumming method. Examples of such formed activated carbon filter cloths are air-conditioned filters, liquid filter cartridges, and gas masks etc. The conventional gumming manufacturing processes of making activated carbon filter cloth are as follows: selecting proper filter cloth and letting it soaked up the special liquid glue first, then covering another filter cloth after evenly agglutinating granular activated carbon or powders to the surface of the filter cloth. Finally, the activated carbon filter cloth is formed and the whole process is finished. But the following disadvantages exist in this manufacturing process illustrated above. Firstly, the manufacturing cost is high. Secondly, due to necessity of the adhesive for attaching the activated carbon to the surface of the filter cloth, the distribution of the carbon powders or particles is not uniform. Thirdly, the activated carbon is susceptible to be peeled off from the surface of the filter cloth due to some factors. Finally, the filter cloth suffers from high pressure drop, low flux, short service life and poor performance.  
      Thus, there is a need for an improved method of manufacturing melt blown carbon fiber filter element and apparatus implemented thereof that does not suffer from the above-mentioned drawbacks.  
     SUMMARY OF THE INVENTION  
      To overcome these disadvantages shown in prior art technology and improve the performance of the filter cloth, the invention provides a new method of making the melt blown style activated carbon fiber filter cartridges and cloths.  
      The invention also provides a set of processing devices used in the method for making the melt blown style activated carbon fiber filter cartridges and cloths.  
      The adopted technical scheme of melt blown style activated carbon fiber filter manufacturing process comprises steps of: delivering polypropylene resin into a plastic pressing machine and melting the polypropylene resin by high temperature into liquid state, then conducting the melted liquid polypropylene to a fiber-injector, spraying the melted liquid polypropylene into divided fibers such that a fiber receiving device is shot by said fibers, using a carbon feeder to transport activated carbon material to the same fiber receiving device, by the movement of the fiber receiving device, the melted polypropylene fiber joins activated carbon evenly and tightly in a interlacing form. Using the manufacturing method described above, a variety of filter elements may be fabricated according to inner and outer diameter size of the filter element to be desired.  
      The invention also provides a set of processing devices used for manufacturing said melt blown style activated carbon filters. The devices include a plastic pressing machine, a fiber-injector, a carbon feeder and a fiber-receiving device. Said plastic pressing machine is utilized to inhale polypropylene plastic resins and melt the polypropylene plastic resins into liquid state, then transfer the melted polypropylene plastic resins to said fiber-injector, said fiber-injector being used for spraying said melted polypropylene plastic resins in form of fibers to said fiber receiving device. The activated carbon feeder device is applied to transport activated carbon powders to the fiber-receiving device. The fiber-receiving device joins the melted polypropylene fibers with the activated carbon powders evenly to produce filter elements.  
      The advantages of the invention are producing activated carbon fiber filter elements by melt blown is simple and economical, which can reduce material consumption and labor cost; process of soaking materials in liquid-gum which exists in conventional method is avoided in the method of the invention; the polypropylene plastic resins and the carbon are self-bonded to each other with no chemical binder, and the polypropylene fiber joins with the activated carbon evenly and tightly; the method of the invention has the capability of producing various activated carbon fiber filter elements with different porous size; in addition, the filter element formed by the method of the invention has good filtration performance, long operating life and low pressure drop.  
      Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:  
       FIG. 1  is an illustration of process of manufacturing melt blown style activated carbon fiber filter elements;  
       FIG. 2  is a perspective view of devices used in manufacturing process shown in  FIG. 1 ;  
       FIG. 3  is a flowchart of the processing shown in  FIGS. 1 and 2 ; and  
       FIG. 4  is a view of a bridge forming manner in which the activated carbon fiber filter elements are formed gradually. 
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS  
      As shown in FIGS.  1  to  4 , activated carbon fiber filter elements such as filter cartridges and filter cloth are manufactured by the method of the invention using materials such as polypropylene and activated carbon. A set of devices used in the method includes: a plastic pressing machine  1 , a fiber-injector  2 , a carbon feeder  4  and a fiber-receiving device  3 . The plastic pressing machine  1  is applied to inhale polypropylene resin  5  and melt it into liquid state then transfer to the fiber-receiving device  3  in a fiber form. The carbon feeder  4  is applied to transport activated carbon  62  to the fiber-receiving device  3 . The fiber-injector  2  has a plurality of output ports  21  used for spraying and dividing the melt polypropylene resin  5  into fibers  61  and making them be transferred to the fiber-receiving device  3 , said fiber-receiving device  3  being capable of joining polypropylene fibers  61  and activated carbon  62  evenly, thus making them wrapped together on the fiber-receiving device  3  to form a filter element. The fiber-receiving device  3  may take different configuration for producing different type of activated carbon fiber filter elements such as spinning configuration for filter cartridge and plane configuration for filter cloth.  
      The method of the invention is performed by the following steps: Step  301  includes inhaling polypropylene resin  5  into plastic pressing machine  1 , then melting polypropylene resin  5  at 280° C., and pressing the polypropylene resin  5  with the operating pressure falling within 2.5 kg-10 kg/cm2 to make the polypropylene resin  5  melted and transferred to the fiber-injector  2 ; followed is Step  302 , which involves spraying the liquid polypropylene resin  5  by the fiber-injector  2  from pluralities of output ports  21  of the fiber-injector  2  to the fiber-receiving device  3  in a fiber form. Then in step  303  which is performed simultaneously with the step  302 , the carbon feeder  4  transports the activated carbon  62  to the fiber-receiving device  3 , said device  3  can adsorb the polypropylene fiber  61  and activated carbon  62  thereto. Then in step  304 , by receiving function of the fiber-receiving device  3 , the polypropylene fiber  61  and the activated carbon  62  are bonded each other to form bridge evenly and tightly. The fiber-receiving device  3  may take different configuration for producing different type of activated carbon fiber filter elements such as spinning configuration for filter cartridge and plane configuration for filter cloth. The final step  305  relates to producing different filter elements according to predefined inner and outer diameter, e.g. column filter element or a plurality of produce polypropylene fiber filter cloth of a fixed size.  
      In the above steps, adjusting the thickness of the polypropylene fiber  61  and the distance of the fiber-receiving device  3  can produce different filtration elements. Because of the multi-layers of polypropylene, the filter apertures are very small, and the filterable particle ≦0.5 μm.  
      This invention adopts bridge-forming method in which the polypropylene fiber  61  and the activated carbon  62  are enwound together. By the carbon feeder  4 , the activated carbon  62  is transferred to the fiber-receiving device  3  and joins the polypropylene fiber  61  under high temperature. The activated carbon  62  is bonded to the polypropylene fiber  61  time and again and both interlace together to form filter apertures even and tightly. When the outer diameter reaches the set size, compound fiber activated carbon filter cartridges are produced or an activated carbon polypropylene fiber filter cloth within a pre-set size is formed.  
      While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.