Patent Publication Number: US-2015061171-A1

Title: Method of manufacturing wound dressing

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a wound dressing and more particularly, to a method of manufacturing the wound dressing which internally containing activated carbon fibers and capable of emitting far-infrared radiation. 
     2. Description of the Related Art 
     Skin is the biggest organism covering the human surface and is the first line defense for protecting the human body against infection of external pathogens and external hurt. When the skin has a wound, to make the wound heal well, a wound dressing is usually used for covering the wound empirically to provide a preferable healing environment and prevent the wound from infection. 
     The empirically common wound dressing, such as gauze or cotton pad, usually has the function of covering the wound and decreasing the external infection only and does not function as promoting tissue regeneration of the wound and effectively improving leakage of tissue fluid. When such conventional wound dressing is covered on a wound having more tissue fluid, it is necessary to replace the wound dressing frequently, so it is a very big burden and trouble for the patient and the healthcare personnel. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a method of manufacturing a wound dressing, which can absorb the liquid leaking from the wound and emit far-infrared rays for helping the wound heal. 
     The foregoing objectives of the present invention are attained by the method, which includes the steps of (a) adding the activated carbon fibers into a foam precursor where each of the activated carbon fibers has a diameter of 2-15 μm and a length of 40-1500 μm, the foam precursor is made of a polymeric material, and the additive amount of the activated carbon fibers is 0.1-5 wt % of the total amount of the activated carbon fibers and the polymeric material; and (b) foaming the foam precursor to make it become an absorbing member having a plurality of pores where the activated carbon fibers partially protrude into the pores. 
     In light of the above, the tissue fluid leaking from the wound can be absorbed by the absorbing member to prevent the wound from soakage and the activated carbon fibers in the absorbing member can emit far-infrared rays to promote blood circulation around the wound to further speed up the healing of the wound. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the first preferred embodiment of the present invention. 
         FIG. 2  is a perspective view of the second preferred embodiment of the present invention. 
         FIG. 3  is a perspective view of the third preferred embodiment of the present invention. 
         FIG. 4  is a perspective view of the fourth preferred embodiment of the present invention. 
         FIG. 5  is a flow chart of the method of the present invention. 
         FIG. 6  is a photo showing the wound dressing of the present invention under an electromicroscope. 
         FIG. 7  is another photo showing the wound dressing of the present invention under an electromicroscope. 
         FIG. 8  is a photo showing the wound dressing of a control group under an electromicroscope. 
         FIG. 9  is another photo showing the wound dressing of a control group under an electromicroscope. 
         FIG. 10  is another photo showing the wound dressing of a control group under an electromicroscope. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Structural features and desired effects of the present invention will become more fully understood by reference to four preferred embodiments given hereunder. However, it is to be understood that these embodiments are given by way of illustration only, thus are not limitative of the claim scope of the present invention. 
     Referring to  FIG. 1 , a wound dressing  1  for covering a wound in accordance with the first preferred embodiment of the present invention is formed of an absorbing member  10  and a plurality of elongated activated carbon fibers. The detailed descriptions and operations of these elements as well as their interrelations are recited in the respective paragraphs as follows. 
     The absorbing member  10  is made of a foamed polymeric material and includes a plurality of pores  12 , as shown in  FIGS. 6 and 7 . The polymeric material can be, but not limited to, polyurethane (PU) resin, polyvinyl ester resin, ethylene vinyl acetate (EVA) resin, or a mixture thereof. 
     The activated carbon fibers  20  are distributed in the absorbing member  10  and partially protrude into the pores  12 , as shown in  FIGS. 6 and 7 . Each of the activated carbon fibers  20  has a diameter of 2-15 μm, preferably 4-10 μm, and a length of 40-1500 μm, preferably 40-1000 μm. If the diameter and length of the activated carbon fiber  20  are smaller than the aforesaid ranges, the activated carbon fiber  20  will be easily fully covered by the absorbing member  10  to fail to protrude into the pore  12 . If the diameter and length of the activated carbon fiber  20  are larger than the aforesaid ranges, respectively, the foaming of the absorbing member  10  will be adversely affected to reduce the structural strength of the absorbing member  10  or even disable foaming of the absorbing member  10 . The activated carbon fibers  20  can be, but not limited to, polyacrylonitrile-based activated carbon fibers, which can be formed by introducing polyacrylonitrile oxidized fibers into humid carbon dioxide gas under the temperature of 700-1200° C. for 1-60 minutes. Besides, the surface of the activated carbon fiber can be loaded with grains of precious metal, such as silver, gold, palladium, platinum, copper, zinc, or a mixture thereof, for antibacterial effect. Among the grains of the precious metals, the grains of silver have the best antibacterial effect. 
     The wound dressing  1  can be covered on the wound located on the surface of the human skin, and the absorbing member  10  having the pores  12  can absorb the tissue fluid leaking from the wound to relieve the soakage of the wound and to decrease the frequency of replacement of the wound dressing  1 . After absorbing external energy, such as thermal energy or optical energy, the activated carbon fibers  20  can release the energy in the format of far-infrared rays to promote blood circulation around the wound to further help the wound heal more quickly. 
     Referring to  FIG. 2 , to prevent the wound dressing  1  from sticking to the wound, the wound dressing  1  of the second preferred embodiment of the present invention further includes a contact layer  30  mounted to one side of the absorbing layer  10 , which is adjacent to the wound, for contact with the wound. In addition, to prevent external source of infection from entering the wound, the wound dressing  1  can further include a breathable layer  40  mounted to one side of the absorbing layer  10 , which is distant from the wound. The breathable layer  40  is made of a material, which is resistant against hydrolysis and wear and tear, easily processed, and highly flexible, and which allows mist other than any liquidized water molecule to pass through to make the surface of the wound adequately moist and make extra mist exhaust to prevent the wound from soakage. 
     In addition, the absorbing member  10  can further contain a therapeutic ingredient  50 , which can be, but not limited to, erythromycin, tetracycline, clindamycin hydrochloride, indochlorhydroxyquin, chlorination quinoline, tolnaftate, centella asiatica, glycerol triacetane, mupirocin, povidone iodine, catechin, chitosan, polyglutamic acid, or a mixture thereof for healing trauma, burn, or scald. 
     Referring to  FIG. 3 , the wound dressing  1  of the third preferred embodiment of the present invention further includes a plurality of absorbing members  10  and  10   a,  one of which contains the activated carbon fibers  20 . In other embodiments of the present invention, the absorbing members  10  and  10   a  may both have the activated carbon fibers  20 . 
     Referring to  FIG. 4 , the wound dressing  1  of the fourth preferred embodiment of the present invention further includes a back lining  60  mounted to one side of the breathable layer  40 , which is distant from the wound. The area of the back lining  60  is larger than that of either of the contact layer  30 , the absorbing member  10 , and the breathable layer  40 . The back lining  60  may have an area, which is not covered by the breathable layer  40  and is coated with pressure-sensitive adhesive for adhering the wound dressing  1  to the human skin. To keep the activity of the back lining  60 , a release paper  70  can be covered on the pressure-sensitive adhesive on the back lining  60 . The release paper  70  can be removed before the wound dressing  1  is adhered to the skin. 
     Referring to  FIG. 5 , a method of manufacturing the primary part of the wound dressing  1  is to add the activated carbon fibers into a foam precursor of the absorbing member where the additive amount of the activated carbon fibers is 0.1-5 wt %, preferably 1-3 wt %, of the total amount of the activated carbon fibers and the foam precursor. If the additive amount of the activated carbon fibers is less than the aforesaid range, the expected effect of promoting healing of the wound will not be reached. If the additive amount of the activated carbon fibers is greater than the aforesaid range, the structural strength of the absorbing member will be easily weakened, and the absorbing member may not be successfully foam-molded. Likewise, the activated carbon fibers can be polyacrylonitrile-based activated carbon fiber formed by introducing polyacrylonitrile oxidized fiber into humid carbon dioxide gas under the temperature of 700-1200° C. for 1-60 minutes. 
     Under the circumstances that the absorbing member is two-component polyurethane ester, the foam precursor includes polyols (e.g. polypropylene glycol) and diisocyanates [e.g. toluene diisocyanate (TDI) or 4,4′-methylenediphenyl diisocyanate (MDI)], and foaming agent. To produce the wound dressing of the present invention, the polyols, the foaming agent, and the activated carbon fibers can be premixed. Secondly, mix the diisocyanate and the aforesaid mixture. Thirdly, put the mixture into a mold for foaming. After the foaming is completed, it can be followed by steps of mold release and cutting to produce the wound dressing of the present invention. It is worth mentioning that the foam precursor can be, but not limited to, PU resin, polyvinyl ester resin, or EVA resin. 
     A wound dressing of the present invention is shown in the electromicroscopic photo of  FIG. 6 , in which the wound dressing is made by the aforementioned method with 2 wt % of the activated carbon fibers having the diameter of 6 μm and the length of 40 μm in average. 
     Another wound dressing of the present invention is shown in the electromicroscopic photo of  FIG. 7 , in which the wound dressing is made by the afore mentioned method with 2 wt % of the activated carbon fibers having the diameter of 6 μm and the length of 1000 μm in average. 
     A wound dressing of the control group is shown in the electromicroscopic photo of  FIG. 8 , in which the wound dressing is made by foaming the precursor with 2 wt % of the granulized activated carbon fibers having the diameter of 20 μm and the length of 35 μm in average. 
     Another wound dressing of the control group is shown in the electromicroscopic photo of  FIG. 9 , in which the wound dressing is made by foaming the precursor with 2 wt % of the activated carbon fibers having the diameter of 4 μm and the length of 9 μm in average. 
     Another wound dressing of the control group as shown in the electromicroscopic photo of  FIG. 10 , in which the wound dressing is made by foaming the precursor with 2 wt % of the activated carbon fibers having the diameter of 6 μm and the length of 5000 μm in average. 
     As known from the aforesaid electromicroscopic photos, in the wound dressing made by the method of the present invention, the absorbing member has better formability and the activated carbon fibers partially protrude into the pores of the absorbing member, as shown in  FIGS. 6 and 7 . Referring to  FIGS. 8 and 9  again, in each of the wound dressings in the control groups, the absorbing member is though well foamed but the shorter activated carbon fibers are fully covered by the absorbing member and fail to protrude into the pores. Besides, in the wound dressing in the control group shown in  FIG. 10 , the activated carbon fibers are excessively long so that they flocculate in the process of foaming and interfere with the molding of the absorbing member. Thus, the activated carbon fibers have less uniformity in the absorbing member. 
     In light of the above, the wound dressing of the present invention has preferable formability and high absorbability for absorbing leakage of excessive tissue fluid and can emit far-infrared rays for promoting blood circulation and quickening the healing of the wound heal. In this way, the wound dressing of the present invention can effectively shorten the time that the wound needs for healing and relieve the healthcare personnel&#39;s burden.