Patent Publication Number: US-4546027-A

Title: Non-woven material for medical compresses

Description:
The present invention relates to a non-woven material whose curly or wavy structure enables it to be used in particular as a medical or surgical compress. 
     At present, medical compresses are obtained from a light fabric--called dressing gauze--(weight between 25 and 28 g/m 2 ) whose manufacture requires the utilization of a costly and inefficient material. This fabric is then folded and cut into several sizes; each compress is then in general wrapped individually and sterilized. 
     Compresses made of conventional gauze are very flat products, adhering to wounds and having quite a low fluid absorption coefficient. In addition, their elasticity and resilience characteristics are very clearly insufficient. 
     The aim of much research work has been to replace the gauze by non-woven materials obtained by a dry process, wet process or so-called &#34;spun-bonded&#34; method and compounds of mixtures of synthetic and/or natural fibers. Although the properties of non-woven compresses are appreciably superior to those made from gauze, particularly as regards non-adhesion to wounds, they nevertheless are still far from meeting requirements as regards absorption. 
     The present invention relates to a non-woven material mitigating the disadvantages of non-woven materials and conventional gauze. Its particular structure enables properties such as high absorption capacity, non-adherence to wounds, elasticity, and resilience to be combined. 
     In general, this non-woven material has a succession of uniformly distributed waves whose anti-nodes are alternatively located above and below the medium plane of the non-woven material. 
     In particular, the continuous anti-nodes of two adjacent waves, located on the same side of the medium plane of the non-woven material, consist of small adjacent pads. 
     According to one embodiment of the invention, the non-woven material is a composite consisting of synthetic netting on which a web of cellulose fibers is fixed, in particular by thermo-bonding. 
    
    
     The invention will be better understood with the aid of the drawings, which represent non-limitative examples of the design of the non-woven material: 
     FIG. 1 is a view of the non-woven material from below; 
     FIG. 2 is a sectional view of FIG. 1 in a plane parallel to the machining direction of the non-woven material; 
     FIG. 3 is a sectional view of FIG. 1 in a plane perpendicular to the machining direction of the non-woven material; 
     FIG. 4 is a perspective view of a non-woven material of a synthetic netting and a cellulose fiber web. 
    
    
     FIG. 1 is a view from below the non-woven material (1) which has a machining direction (2), corresponding to the longitudinal direction of the manufacture of said non-woven material, and a crosswise direction (3) perpendicular to the machining direction (2). This non-woven material (1) comprises evenly spaced waves or curls positioned along the lines (5) parallel to the machining direction (2). 
     FIG. 2, which is a sectional view of FIG. 1 along 2--2, in a plane parallel to the machining direction (2) shows that the non-woven material has waves (4) whose anti-nodes (6,7) are alternatively above and below the median plane (8). 
     FIG. 3 which is a sectional view of FIG. 1 along 3--3, in a plane perpendicular to the machining direction (2) shows that the contiguous anti-nodes (9,10) of adjacent waves consist of small adjacent pads (11,12) located on the same side of the median plane (8) of the non-woven material. Beyond the sectional plane is seen an outline of the pads located below the median plane (8). The height and width of these pads are between 0.1 and 3 mm. 
     FIG. 4 shows a preferred embodiment of the invention; the non-woven material consists of a synthetic netting (13) consisting of filaments (15) of a first polymer inside a sheath of a second polymer and connected by fine lamellas (16) of a second polymer, forming a netting on the surface of which is deposited a cellulose fiber web (14). 
     The web (14) is thermo-bonded to the netting (13); the non-woven material, therefore, does not include any chemical binder and can, therefore, be used both as a medical and a surgical compress. 
     According to a preferred embodiment of the invention, the synthetic netting (13) is a double-stretched netting comprising in the machining direction (2) parallel polyamide filaments (15) separated by a uniform distance between 0.1 and 3 mm and connected to one another by narrow strips of polypropylene (16), separated regularly by a distance between 0.1 and 3 mm and perpendicular to the filaments (15). The web (14) of the cellulose fibers consists of a cotton fiber web. 
     In addition, this non-woven material has the advantage of being lighter in weight than conventional gauze. The netting (13) has a weight of between 5 and 15 g/m 2 , preferably 7 g/m 2  and the cellulose fiber web (14) a weight between 10 and 20 g/m 2 , preferably 16 g/m 2 . Its bulk density is less than 0.15--preferably 0.1, and its absorption capacity is greater than 13 cm 3  /g--preferably 16 cm 3  /g. 
     The table below gives the results of measurements made on non-woven material according to the invention, on conventional gauze, and on a commerical non-woven material called PELY-TEX: 
     
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         Non-Woven Material                                               
         According To The     PELY-TEX                                    
         Invention    Gauze   23VI                                        
______________________________________                                    
Weight g/m.sup.2                                                          
           24             25      23.7                                    
Thickness mm (1)                                                          
           2.40           1.50    1.40                                    
Density    0.1            0.17    0.17                                    
Absorption Rate                                                           
           8              60      45                                      
sec. (2)                                                                  
Absorption 16             12      12.7                                    
Coefficient                                                               
cm.sup.3 /g (3)                                                           
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 (1) The thickness is defined as the thickness of 10 superimposed sheets  
 measured under a pressure of 20 g/cm.sup.3.                              
 (2) The absorption rate is defined as the time taken by a drop of water o
 1/20 cm.sup.3 deposited on the surface of said nonwoven material with a  
 pipette to penetrate the nonwoven material.                              
 (3) The absorption coefficient is determined according to the CODEX      
 standard applicable to cotton wool.                                      
 
    
     The very special structure of the non-woven material according to the invention enables compresses to be manufactured which are: 
     very absorbent because of the pads described above and the presence of the cellulose fiber web; 
     non-adherent to wounds because of a mode of folding such that the parts designed to come into contact with the wound consists of the bare synthetic netting; 
     elastic because of the presence of uniformly distributed waves; 
     resilient because of the framework consisting of the synthetic netting.