Patent Publication Number: US-2005132754-A1

Title: Anti-bacterial medical waterproof material and sheet made of the same

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an anti-bacterial waterproof material made of a circular knitted fabric woven with a nylon yarn containing an ultra-micro powder of silver effective in controlling the growth of various bacteria from the moisture associated with patient use, and more particularly, to a medical sheet made of the material of the present invention.  
      2. Description of the Related Art  
      As our society ages, the number of the bedridden elderly is increasing annually. Many of these patients require an additional medical waterproof sheet placed beneath their lower back on a bed or other support surface.  
      Typical waterproof sheets used in medical facilities, such as nursing homes and hospitals are placed in the center of a mattress of a bedridden patient to prevent sweat, bodily fluid and/or waste of the patient from penetrating the mattress or support.  
      At the core of these conventional waterproof sheets is a polyurethane film to which a fabric is attached. This polyurethane film blocks the moisture of the patient&#39;s fluids from penetrating into the mattress or support.  
      However, these conventional waterproof sheets do not eliminate odor, are not anti-bacterial and are not designed to control the growth of bacteria such as MRSA,  staphylococcus aureus, pneumobacillus  and  E.coli  bacteria. See Japanese Unexamined Patent Application 7-39564.  
      Thus, there is a need for a medical anti-bacterial waterproof material that can be used as a sheet or other item which can control bacterial growth and/or eliminate odor.  
     SUMMARY OF THE INVENTION  
      An object of the present invention is to provide a waterproof material that can be made into a sheet or other product for medical use to eliminate odor and bacterial growth.  
      Another object of the present invention is to produce a low cost, easily assembled waterproof sheet of a circular knitted fabric woven with a nylon yarn containing an ultra-micro powder of silver ions to control bacterial growth and eliminate odor.  
      In accomplishing these and other objects of the present invention there is provided a waterproof material comprising a knitted fabric woven from a first yarn and a second yarn, the first yarn being a nylon filament containing ultra-micro silver ions and the second yarn being a polyester yarn. The fabric is made of approximately 20 to 40% of the first yarn and 60-80% of the second yarn.  
      In accomplishing these and other objects of the present invention there is provided an antibacterial waterproof sheet having a multilayer construction for controlling bacterial growth, eliminating odor and resisting wear, comprising a polyurethane film having an upper and lower side forming an innermost layer. A layer of polyurethane adhesive is disposed on each upper and lower side of the film. A layer of knitted material is disposed on each layer of adhesive forming opposed outer layers of the sheet. The knitted material is woven from a first yarn and a second yarn. The first yarn is a polyester yarn and the second yarn is a nylon filament containing ultra-micro silver ions.  
      These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiment relative to the accompanied drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates a length of nylon yarn containing the ultra-micro powder of silver ions used in the material of the present invention.  
       FIG. 2  is a perspective view of the fabric of the present invention.  
       FIG. 3  is a perspective view of an anti-bacterial waterproof sheet made of the fabric and according to the present invention.  
       FIG. 4  is a cross-section of the sheet of  FIG. 3  taken along line I-I.  
       FIG. 5  is a perspective view of a mattress with the anti-bacterial waterproof sheet of the present invention placed thereon.  
       FIG. 6  is a perspective view of a pillow with the anti-bacterial waterproof sheet of the present invention placed thereon.  
       FIG. 7  is a perspective view of a bed with the anti-bacterial waterproof sheet of the present invention placed thereon.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT  
      Referring to  FIGS. 1-3 , the waterproof antibacterial material of the present invention is made of a circular knitted fabric  14  having a gauge of 28-32 weaves of fiber, one measurement of fiber equals one weave, 1 gauge of fiber. The fabric is circular knitted to increase softness, elasticity and flexibility.  
      The knitted fabric is woven, approximately 20% to 40%, with a first nylon yarn  10  having a length of 70D/24F to 140D/48F. Nylon yarn is desirable because of its hydrophilic properties, improving fluid absorption. Moreover, higher price and health concerns are limited by maximizing the content of the fabric to 20-40% nylon yarn. Use of a nylon yarn in excess of 40% can irritate or damage sensitive skin.  
      The yarn  10  is shown in  FIG. 1  and is a filament containing ions of ultra-micro silver powder  12 . The silver powder ions  12  are preferably 1 micron or smaller in size. Fabric  12  is comprised approximately 60-80% of a second 100% polyester yarn having a length of 70D/24F to 140D/48F for example, 450 meters with a quantity of 0.05 grams or 1 denier. This yarn material facilitates the generation of the silver ions from the ultra-micro silver powder  12 . It should be appreciated that other yarns having the appropriate gauge and properties can be used.  
      As shown in  FIGS. 3 and 4 , an antibacterial waterproof sheet  20  can be made using the material of the present invention. Referring to  FIG. 4 , the fabric  20  is applied to a polyurethane film  18  with a compatible polyurethane adhesive  16 . Film  18  has a preferable thickness of 0.5 to 0.15 mm. The adhesive  16  is applied to the fabric which is then heated and pressed onto film  18 .  
      The sheet is formed in a continuous motion, for example, by use of a pressure roller and pressure belt. Pressure within the range of 2.5 to 3.0 kg/m 2 , a heating temperature range of 75 to 85° C., and a speed of 0.9 to 1.0 m/min can be used to form the sheet.  
      A layer of fabric  20  is disposed on each side of film  18 . Due to the multilayer construction, both sides of sheet  20  can be used for convenience, economy and practicality.  
      Accordingly, the waterproof sheet of the present invention has a multi-layer construction and enhanced resistance to bacterial growth, odor and wear from repeated washing and drying. In use, the sheet will prevent the moisture of sweat, bodily fluids or waste from infiltrating the mattress, futon or other support upon which it is placed.  
      The properties of the medical waterproof sheet of the present invention has been determined as follows: 
          Water resistance: 1500 mm or more (JISL 1092)     Water vapor permeability: 1,000 g/m 2 /24 hrs or more (JISL 1099)     Full thickness: 0.5 to 0.75 mm (dial gauge)     Full weight: 200 to 330 g/m 2  (10 cm×10 cm conversion)     Cleaning: sample sheet withstood 100 washings with water (no dry cleaning)        

       FIGS. 5-7  illustrate working examples of the antibacterial medical waterproof sheet according to the present invention. As shown in  FIGS. 5 and 7 , sheet  20  is placed at the center of a mattress  30 , with both ends tucked thereunder.  FIG. 7  illustrates the sheet of the present invention on mattress  30  of bed  36 .  FIG. 6  illustrates the sheet of the present invention as used on a pillow  32 .  
      It should be appreciated that the waterproof sheet  20  of the present invention is not limited to medical applications, be can also be used in other environments and applications. Moreover, a pillow or mattress can be cover on its entire surface with the fabric of the present invention. Other contemplated uses and/or applications for the fabric and sheet of the present invention can include a cover for a stretcher, a pillowcase or protective cover for a carpet/rug to protect the same from moisture and stain.  
      The fabric and sheet of the present invention is especially effective in controlling the growth of various bacteria, including MRSA,  staphylococcus aureus, pneumobacillus  and  E.coli  bacteria. It also prevents odors associated with bacterial growth. Various anti-bacterial tests were conducted.  
               TABLE 1                          [Test Item]       Anti bacterial test       [Bacteria]       MRSA Methicillin resistant  Staphylococcus aureus  IID 1677       [Test Method]       Standardized test method       [Test Results]                                 Planted bacteria count [A]   2.4 × 10 4     Log A 4.4       Bacteria count on untreated fabric [B]   1.3 × 10 7     Log B 7.1                         (Untreated fabric: Standard cotton fabric)       Log B − Log A = 2.7 &gt; 1.5 ... Test was effective.       Active bactericidal level = Log A − Log C       Active bacteriostatic level = Log B − Log C                                         Bacteria count   Active bactericidal   Active bacteri-       Sample   Log C   level   ostatic level               With silver yarn   1.3   3.1   5.8                  
 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
               
             
            
               
                 [Test Item] 
               
               
                 Anti bacterial test 
               
               
                 [Bacteria] 
               
               
                   Staphylococcus aureus  ATCC 6538P 
               
               
                 [Test Method] 
               
               
                 JIS L1902 quantitative test (standardized test method) 
               
               
                 [Test Results] 
               
               
                   
               
            
           
           
               
               
               
            
               
                 Planted bacteria count [A] 
                 2.3 × 10 4   
                 Log A 4.4 
               
               
                 Bacteria count on untreated fabric [B] 
                 1.3 × 10 7   
                 Log B 7.1 
               
               
                   
               
            
           
           
               
            
               
                 (Untreated fabric: Standard cotton fabric) 
               
               
                 Log B − Log A = 2.7 &gt; 1.5 ... Test was effective. 
               
               
                 Active bactericidal level = Log A − Log C 
               
               
                 Active bacteriostatic level = Log B − Log C 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Bacteria count 
                 Active bactericidal 
                 Active bacteri- 
               
               
                 Sample 
                 Log C 
                 level 
                 ostatic level 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Polyester 100% 
                 5.5 
                 −1.1 
                 1.6 
               
               
                 Polyester 100% 
                 1.3 
                 3.1 
                 5.8 
               
               
                 (with silver) 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
               
             
            
               
                 [Test Item] 
               
               
                 Anti bacterial test 
               
               
                 [Bacteria] 
               
               
                   Klebsiella pneumoniae  ATCC 4352 
               
               
                 [Test Method] 
               
               
                 Standardized test method 
               
               
                 [Test Results] 
               
               
                   
               
            
           
           
               
               
               
            
               
                 Planted bacteria count [A] 
                 1.9 × 10 4   
                 Log A 4.3 
               
               
                 Bacteria count on untreated fabric [B] 
                 2.9 × 10 7   
                 Log B 7.5 
               
               
                   
               
            
           
           
               
            
               
                 (Untreated fabric: Standard cotton fabric) 
               
               
                 Log B − Log A = 3.2  &gt; 1.5 ... Test was effective. 
               
               
                 Active bactericidal level = Log A − Log C 
               
               
                 Active bacteriostatic level = Log B − Log C 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Bacteria count 
                 Active bactericidal 
                 Active bacteri- 
               
               
                 Sample 
                 Log C 
                 level 
                 ostatic level 
               
               
                   
               
               
                 With silver yarn 
                 1.3 
                 3.0 
                 6.2 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                   
               
             
            
               
                 [Test Item] 
               
               
                 Anti bacterial test 
               
               
                 [Bacteria] 
               
               
                   Escherichia coli   NBRC 3301 
               
               
                 [Test Method] 
               
               
                 Standardized test method 
               
               
                 [Test Results] 
               
               
                   
               
            
           
           
               
               
               
            
               
                 Planted bacteria count [A] 
                 2.1 × 10 4   
                 Log A 4.3 
               
               
                 Bacteria count on untreated fabric [B] 
                 3.1 × 10 7   
                 Log B 7.5 
               
               
                   
               
            
           
           
               
            
               
                 (Untreatcd fabric: Standard cotton fabric) 
               
               
                 Log B − Log A = 3.2 &gt; 1.5 ... Test was effective. 
               
               
                 Active bactericidal level = Log A − Log C 
               
               
                 Active bacteriostatic level = Log B − Log C 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Bacteria count 
                 Active bactericidal 
                 Active bacteri- 
               
               
                 Sample 
                 Log C 
                 level 
                 ostatic level 
               
               
                   
               
               
                 With silver yarn 
                 1.3 
                 3.0 
                 6.2 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                   
               
               
                   
               
             
            
               
                 1 
                 [A] Bacteria count on untreated sample immediately after planting (Log A) 
               
               
                   
                 [B] Bacteria count on untreated sample after 18 hour incubation (Log B) 
               
               
                   
                 [C] Bacteria count on treated sample after 18 hour incubation (Log C) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 2 
                   
                   
                 
                   Staphylococcus 
                 
                 
                   Klebsiella 
                 
                 
                   Escherichia 
                 
                 
                   Pseudomonas 
                 
               
               
                   
                   
                 MRSA 
                 
                   aureus 
                 
                 
                   pneumoniae 
                 
                 
                   coli 
                 
                 
                   aeruginosa 
                 
               
               
                   
               
               
                   
                 Active bacteriostatic level 
                 5.8 
                 5.8 
                 6.2 
                 6.2 
                 1.9 
               
               
                   
                 Log B-Log C 
               
               
                   
                 Effectiveness in controlling 
                 1/630,000 
                 1/630,000 
                 1/1,600,000 
                 1/1,600,000 
                 1/80 
               
               
                   
                 bacterial growth (compared 
               
               
                   
                 to untreated fabric) 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Criteria for evaluating bacteria growth/odor control: (Log for  staphylococcus aureus  must be 2.2 or higher; 
               
               
                   
                 generally 1/160 or less) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 3 
                   
                   
                 
                   Staphylococcus 
                 
                 
                   Klebsiella 
                 
                 
                   Escherichia 
                 
                 
                   Pseudomonas 
                 
               
               
                   
                   
                 MRSA 
                 
                   aureus 
                 
                 
                   pneumoniae 
                 
                 
                   coli 
                 
                 
                   aeruginosa 
                 
               
               
                   
               
               
                   
                 Active bactericidal level 
                 3.1 
                 3.1 
                 3.0 
                 3.0 
                 −0.9 
               
               
                   
                 Log A-Log C 
               
               
                   
                 Effectiveness in bactericidal 
                 1/1,260 
                 1/1,260 
                 1/1,000 
                 1/1,000 
                 8 times 
               
               
                   
                 activity (compared to initial 
               
               
                   
                 bacteria count) 
               
               
                   
               
            
           
           
               
               
            
               
                   
                 Criteria for evaluating sterilization: Active bactericidal level must be: Log C &lt; Log AC 0 (bacteria 
               
               
                   
                 count must be less than initial count) 
               
            
           
           
               
               
            
               
                 4 
                 The SEK (Japan Textile Evaluation Technical Council) mark specifies the following. 
               
               
                   
                 [Bacteria to be Tested] include: 
               
            
           
           
               
               
            
               
                   
                 Bacterial growth control treatment 
               
            
           
           
               
               
               
               
            
               
                   
                   
                   
                 Specific 
               
               
                   
                 Antibacterial/anti 
                 General 
                 application 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Bacteria to be tested for bacteria growth/odor control 
                 odor treatment 
                 application 
                 (medical) 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 
                   Staphylococcus 
                 
                 IID 
                 1677 (MRSA) 
                 — 
                 — 
                 □ 
               
               
                   
                 
                   Staphylococcus aureus 
                 
                 ATCC 
                 6538P (*) 
                 □ 
                 □ 
                 □ 
               
               
                   
                 
                   Klebsiella pneumoniae 
                 
                 ATCC 
                 4352 (*) 
                 — 
                 □ 
                 □ 
               
               
                   
                 
                   Eseherichia coli 
                 
                 IFO 
                 3301 (*) 
                 — 
                 □ 
                 □ 
               
               
                   
                 
                   Pseudomonas aeruginosa 
                 
                 IFO 
                 3080 (*) 
                 — 
                 □ 
                 □ 
               
               
                   
               
               
                   Note:    
               
               
                   □: Required: □: Optional: —: Not applicable    
               
            
           
         
       
     
      Although the present invention has been described in relation to particular embodiments thereof, many other variations and modifications and other uses will become apparent to those skilled in the art. It is preferred therefore, that the present invention be limited not by the specific disclosure herein, but only by the appended claims.