Self-sealing valve for inflated bodies
TECHNICAL FIELD 
     This invention relates to a novel and improved self-sealing valve for an inflated body and is particularly suitable for lighter-than-air balloons containing helium or the like. 
     BACKGROUND ART 
     Currently, there are a number of techniques used to seal the valves in inflatable bodies. The most common technique in lighter-than-air helium filled balloons is to use a valve that relies on the internal pressure of the inflated body and the molecular attraction of certain plastic film materials to achieve a seal. 
     Gregory U.S. Pat. No. 1,008,641 discloses a self-sealing valve in a balloon comprising a generally flat tube extending through and sealed to the wall of the balloon with the sides of the flat tube remaining in contact to form a seal except when they are forcibly separated. 
     Davenport U.S. Pat. No. 2,597,924 discloses a self-sealing valve in a bladder comprising a pair of layers of plastic sheet material which relies on the internal plastic and the molecular adhesion of the material to form the seal. While these prior attempts have been successful to some degree, they still allow an unacceptably high rate of leakage particularly when used with lighter than air gases such as helium which gas tends to leak through microscopic openings. 
     DISCLOSURE OF THE INVENTION 
     A self-sealing valve for an inflatable body is disclosed. The valve disclosed includes a self-sealing valve member which extends through and is sealed to inner wall portions of an inflatable body. The valve member has opposed wall portions normally superposed on one another so that the wall portions can be forcibly separated to provide a flow passage through the valve member. The inside of the wall portions are provided with a coating of a viscid, non-hardening material, preferably a polypropylene glycol which material will flow into any microscopic openings along the flow passage to prevent an exiting gas flow from the body. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The details of this invention will be described in connection with the accompanying drawings in which: 
     FIG. 1 is a perspective view of an inflated body having a self-sealed valve embodying features of the present invention; 
     FIG. 2 is a sectional view taken along line 2--2 of FIG. 1 showing a plan view of the valve in the inflated body; 
     FIG. 3 is an enlarged sectional view taken along lines 3--3 of FIG. 1; 
     FIG. 4 is an enlarged sectional view taken along lines 4--4 of FIG. 3; 
     FIG. 5 is an enlarged sectional view taken along lines 5--5 of FIG. 3; 
     FIG. 6 is an enlarged sectional view taken along the same lines as in FIG. 5 showing the valve in an opened position. 
    
    
     DETAILED DESCRIPTION 
     Referring now to FIG. 1, there is shown an inflated body 11 in the form of an inflated balloon with a self-sealing valve 12 according to the present invention. The inflatable body 11 shown is made of two identically shaped, circular, flexible panel members 14 and 15 preferably of a flexible, plastic sheet material that is impervious to gas flow therethrough. The panel members are joined, preferably by heat seaming along and inwardly of the marginal edge at a seam 17. The valve 12 extends through the seam 17 so that an inner valve portion 18 is inside the inflated body and an outer valve portion 19 is outside the inflated body. 
     The valve 12 is comprised of two relatively long and narrow, generally rectangular, flexible sheet members 23 and 24, made preferably of a gas-impervious plastic film or gas-impervious sheet material superposed one on another. The films are selected to provide a relatively large degree of rigidity and have a tendency to return to the flat condition as well as having a high degree of molecular attraction for themselves. A preferred material is a low density polyethylene/nylon/low density polyethylene laminate, although satisfactory results have also been achieved with other materials including polyurethane and low density polyethylene materials. 
     The sheet members 23 and 24 are best sealed together along two substantially parallel spaced seams 26 and 27. This provides opposed wall portions inside the seams that define a flow passage 28 through the valve when the wall portions are forcibly separated so that a gas will flow between a fill feed end 31 and a fill discharge end 32. 
     A coating 33 is placed between the two sheet members 23 and 24 at inner valve portion 18 inside the body to seal the valve against leakage. This coating, preferably is a viscid, non-hardening sealing composition. A composition found suitable is essentially a polyglycol which is viscid at room temperatures. The composition consists essentially of: ##STR1## where n varies from 5 to 67 and having an average molecular weight from 400 to 4000. The composition that was found to be particularly effective is identified as polyglycol P2000, has an n of 32, and an average molecular weight of 2000. 
     In the assembly of the valve member into the balloon, this is done prior to making the balloon. The two panels 14 and 15 are placed or superposed one on another and the valve 12 is inserted in place. A release coating 38 of a suitable material is provided between the two sheet members at the outer portion 19. The thickness of the release coating 38 is greatly exaggerated in thickness in the drawing for purposes of illustration. A preferred practice is to use a silicon ink and print same on the film. This printed coating is the full width of the two sheets along an outer end portion outside the balloon and seams 26 and 27 terminate a selective distance short of the outr extremities so in plan the pattern of the film is somewhat T-shaped being wider at the outer end and narrower along the seams. The seam 17 is then formed using conventional heat sealing equipment. The release coating 38 does not allow the seal to traverse and seal the valve members together so that the flow passage 28 may be established. In use, a rigid tubular member 35 is inserted through the valve to form flow passage 28 and a pressurized gas such as helium is introduced via the valve into the body 11. When the tubular member 35 is removed, the opposed wall portions of the sheet members 23 and 24 come together and coating 33 will tend to flow into any microscopic openings between the opposed wall portions and along the seams 26 and 27 to prevent an exiting gas flow through the body 11 when the body is inflated. This has been found to be particularly effective in minimizing leakage of helium and light gases in helium inflated balloons. 
     Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.