Child-resistant safety closure

Abstract

Safety screw-closure device for a container provided with an outer screw thread opening, which is made up of two coaxial caps, nested one inside the other, one of them, an outer cap, being able to turn the other, an inner one, by axial pressure and turning: the outer cap comprising, on the inner surface of one of its walls, mutual-engagement means; the inner cap comprising a screw thread on the inner surface of its cylindrical side wall and mutual-engagement means on the outer surface of its wall, facing the wall of the inner cap comprising the mutual-engagement means; and an elastic means disengaging the mutual-engagement means of the walls of the two inner and outer caps, placed between the upper end walls of the two caps, and made of a material of different composition from the composition of the caps.

1 . A safety screw-closure device for a container provided with an outer screw thread opening, which is made up of two coaxial caps made of thermoplastic polymer materials, nested one inside the other, one being an outer cap and the other an inner cap, each formed of a cylindrical side wall and of an upper end wall closing the cylindrical side wall: 
 the outer cap comprising, on its inner surface, mutual-engagement means allowing it to turn the inner cap, by the application of an axial-pressure/turning mechanical torque;    the inner cap comprising a screw thread on the inner surface of its cylindrical side wall and mutual-engagement means corresponding to those of the outer cap on its outer surface, allowing it to be turned by the outer cap, when the latter is subjected to an axial-pressure/turning mechanical torque;    an elastic means for disengaging the mutual-engagement means of the inner and outer caps when the axial-pressure/turning mechanical torque ceases to be applied to the outer cap;    means of guiding of the inner and outer caps ensuring their coaxiality,    characterized in that the elastic disengaging means:    is located between the upper end walls of the inner and outer caps,    is formed of a shape-memory thermoplastic polymer material of different composition from the compositions of the materials constituting the caps themselves.    
     
     
         2 . A safety screw-closure device for a container provided with an outer screw thread opening, which is made up of two coaxial caps made of thermoplastic polymer materials, nested one inside the other, one being an outer cap and the other an inner cap, each formed of a cylindrical side wall and of an upper end wall closing the cylindrical side wall, consists in that: 
 the outer cap comprises, on the inner surface of its upper end wall, mutual-engagement means allowing it to turn the inner cap, by the application of an axial-pressure/turning mechanical torque;    the inner cap comprises a screw thread on the inner surface of its cylindrical side wall and mutual-engagement means corresponding to those of the outer cap on the outer surface of its upper end wall, allowing it to be turned by the outer cap, when the latter is subjected to an axial-pressure/turning mechanical torque;    means of guiding of the inner and outer caps ensuring their coaxiality,    an elastic means of disengaging of the mutual-engagement means of the upper end walls of the inner and outer caps when the axial pressure-turning mechanical torque ceases to be applied to the outer cap, this elastic disengaging means: 
 being located between the upper end walls of the inner and outer caps,  
 and being made of a shape-memory thermoplastic polymer material of different composition from the compositions of the materials constituting the caps themselves.  
   
     
     
         3 . A safety screw-closure device for a container provided with an outer screw thread opening, which is made up of two coaxial caps made of thermoplastic polymer materials, nested one inside the other, one being an outer cap and the other an inner cap, each formed of a cylindrical side wall and of an upper end wall closing the cylindrical side wall, consists in that: 
 the outer cap comprises, on the inner surface of its cylindrical side wall, mutual-engagement means allowing it to turn the inner cap, by the application of an axial-pressure/turning mechanical torque;    the inner cap comprises a screw thread on the inner surface of its cylindrical side wall and mutual-engagement means corresponding to those of the outer cap on the outer surface of its cylindrical side wall, allowing it to be turned by the outer cap, when the latter is subjected to an axial-pressure/turning mechanical torque;    means of guiding the inner and outer caps to ensure their coaxiality;    an elastic means of disengaging the mutual-engagement means of the cylindrical side walls of the inner and outer caps when the axial-pressure/turning mechanical torque ceases to be applied to the outer cap, this elastic disengaging means: 
 being located between the upper end walls of the inner and outer caps,  
 and being made of a shape-memory thermoplastic polymer material of different composition from the compositions of the materials constituting the caps themselves.  
   
     
     
         4 . Device according to one of claims  1 ,  2  or  3 , characterized in that the shape-memory elastic means is not attached to either of the surfaces of the upper end walls.  
     
     
         5 . Device according to one of claims  1 ,  2  or  3 , characterized in that the shape-memory elastic means is secured to one or the other of the surfaces of the upper end walls.  
     
     
         6 . Device according to one of claims  1 ,  2  or  3  and to at least one of claims  4  and  5 , characterized in that the shape-memory elastic means is produced by means of at least one of the shape-memory elastic materials chosen from the group consisting of at least one elastomer.  
     
     
         7 . Device according to  claim 6 , characterized in that the shape-memory elastic means is produced from materials chosen from the group consisting of elastomers of the natural rubber and synthetic rubber type, used alone or in blends.  
     
     
         8 . Device according to  claim 7 , characterized in that the elastic means is preferably made from materials chosen from the group of elastomers formed of isobutylene/isoprene, ethylene-vinyl acetate (EVA), ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer (EPDM), ethylene-acrylic esters (EMA-EEA), fluoropolymers, polybutadienes, styrene-butadiene copolymers (SBR), polyester and polyurethane rubbers, silicones, styrene-butadiene-styrene (SBS) and styrene-isoprene-styrene (SIS) styrene rubbers, employed alone or in blends.  
     
     
         9 . Device according to one of claims  1 ,  2  or  3  and  4  to  8 , characterized in that the shape-memory elastic means has the form of a volume, of the roughly cylindrical, truncated-cone, cylindro-truncated, cylindro-hemispherical, or hemispherical type, of which the diameter is adapted to that of the device and of which the height is at least equal to the minimum distance necessary for the mutual-engagement means of the outer and inner caps not to be in an engaged position.  
     
     
         10 . Device according to  claim 9 , characterized in that the volume of the shape-memory elastic means is a solid volume.  
     
     
         11 . Device according to  claim 9 , characterized in that the volume of the shape-memory elastic means is a hollow volume.  
     
     
         12 . Device according to  claim 11 , characterized in that the hollow volume of the shape-memory elastic means is perforated.  
     
     
         13 . Device according to one of claims  1 ,  2  or  3  and according to at least one of  claims 5  to  12 , characterized in that the shape-memory elastic means is secured to one or the other of the upper end walls by bonding or overmolding.  
     
     
         14 . Device according to one of claims  1 ,  2  or  3  and according to at least one of claims  4 ,  5  and  8  to  13 , characterized in that the shape-memory elastic means is produced using a thermoplastic polymer foam.  
     
     
         15 . Device according to one of claims  1 ,  2  or  3  and according to at least one of  claims 4  to  14 , characterized in that the thermoplastic polymer material used to form the inner and outer caps is chosen from the group consisting of: polyethylenes, polypropylenes, ethylene-propylene copolymers and blends thereof, polyamides, polystyrenes (PS), acrylonitrile-butadiene-styrene copolymers (ABS), styrene-acrylonitrile copolymers (SAN), polyvinylchlorides (PVC), polycarbonate (PC), polymethylmethacrylates (PMMA), polyethylene terephthalates (PET).  
     
     
         16 . Device according to one of claims  1  or  2  and according to at least one of  claims 4  to  15 , characterized in that when the mutual-engagement means are fitted on the inner surface of the upper end wall of the outer cap and on the outer surface of the upper end wall of the inner cap, these means are chosen from those consisting of teeth placed in a ring, blades of square, rectangular or triangular cross section, in a radial position, the radial length of which is at most equal to the radius of the surface receiving the mutual-engagement means less the radius of the base area of the geometric volume of the elastic means.  
     
     
         17 . Device according to one of claims  1  or  2  and according to at least one of  claims 4  to  15 , characterized in that when the mutual-engagement means are fitted simultaneously on the facing surfaces of the cylindrical side walls and on the upper end surfaces of the inner and outer caps, the mutual-engagement means are successive ribs forming blades extending radially over at least one of the appropriate surfaces of the upper end walls of the caps in the form of a radial grooving the radial length of which is at most equal to the radius of the surface receiving the mutual-engagement means less the radius of the base area of the geometric volume of the elastic means.  
     
     
         18 . Device according to one of claims  1  or  3  and according to at least one of  claims 4  to  15 , characterized in that when the mutual-engagement means are fitted on the inner surface of the cylindrical side wall of the outer cap and on the outer surface of the cylindrical side wall of the inner cap, the mutual-engagement means are chosen from the group consisting of blades of square, rectangular, triangular cross section, present on at least part of the height of said side wall and fitted along the generatrices, or notched rings present at the periphery of said concerned surfaces.  
     
     
         19 . Device according to one of claims  1 ,  2  or  3  and according to at least one of  claims 4  to  18 , characterized in that the mutual-engagement means fitted on the facing surfaces of the outer and inner caps have the same morphology or different morphology.  
     
     
         20 . Device according to one of claims  1  or  2  and according to at least one of  claims 4  to  16 , characterized in that the mutual-engagement means placed facing each other on the inner surface of the upper end wall of the outer cap and on the outer surface of the upper end wall of the inner cap are formed, on each of these surfaces, of a ring of teeth, of which the apparent diameter, smaller than that of the caps, is preferably the same for each of the rings.  
     
     
         21 . Device according to  claim 20 , characterized in that the teeth of the mutual-engagement rings have a parallelepipedal shape ending, at their mechanical-engagement end, in two symmetric oblique planes separated from one another by a horizontal plane.  
     
     
         22 . Device according to  claim 20 , characterized in that the teeth of the mutual-engagement rings have a parallelepipedal or cylindrical shape, ending at their mechanical-engagement end, in a hemisphere or a cone frustum.  
     
     
         23 . Device according to at least one of  claims 20  to  22 , characterized in, as a preference, the number of teeth present in each ring is at least four teeth per ring, and the ratio of the number of teeth to the diameter in mm of the ring is comprised between 0.15 and 0.5.  
     
     
         24 . Device according to one of claims  1 ,  2  or  3  and according to at least one of  claims 4  to  23 , characterized in that the means of guiding the outer cap with respect to the inner cap are present on one and/or the other of the cylindrical side walls of each of the caps, on the outer surface of the inner cap and/or on the inner surface of the outer cap.  
     
     
         25 . Device according to  claim 24 , characterized in that the guiding means consist of blades of square, rectangular, triangular cross section present on the cylindrical side wall and fitted according to generatrices of said wall.  
     
     
         26 . Device according to one of claims  1 ,  2  or  3  and according to at least one of claims  4  and  23 , characterized in that the means of guiding the outer cap with respect to the inner cap are also and simultaneously means for allowing the inner cap to be turned by the outer cap only in the screwing direction and are preferably present over the entire height of the cylindrical side walls of the two caps.  
     
     
         27 . Device according to  claim 25 , characterized in that the means for guiding and turning simultaneously the inner cap in the screwing direction using the outer cap are blades having the appearance of a wave of triangular or rectangular section, the origin of which lies on a generatrix of the cylindrical side surfaces, and the end of which is directed in an oblique plane: 
 in the direction with centripetal tendency, when the blades are on the inner surface of the cylindrical side wall of the outer cap,    in the direction with centrifugal tendency, when the blades are on the outer surface of the cylindrical side wall of the inner cap.