Composite can
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to containers and, more specifically, to a paperboard container for fluent materials. 
     Packaging of fluent materials in containers formed of paperboard or like materials is well known in the art as, for example, Hollingshead U.S. Pat. No. 2,603,400, Kasdorf U.S. Pat. No. 2,126,116 and Meyer-Jagenberg U.S. Pat. No. 1,915,027. Such containers, however, suffer, to varying degrees, from problems relating to leakage, difficulty of opening, poor stackability, and poor pourability. The pouring problem is alleviated, to some extent, in containers having an erectable pouring spout, such as McGinnis U.S. Pat. No. 2,593,778, Davidson Jr. et al U.S. Pat. No. 2,327,024 and Karlsson-Ygger U.S. Pat. No. 2,058,592. Likewise, the openability problem has been attacked in containers such as Martin U.S. Pat. No. 2,325,145 and Milmoe U.S. Pat. No. 3,019,191 which include end closures having a self-opening feature. 
     Despite these efforts, no paperboard container, with the exception of a few specialized containers such as milk cartons, has gained substantial market acceptance for the packaging of fluent products. Rather, a compromise solution has been widely adopted, comprising the combination of a paperboard body or sidewall and metal end panels in what is commonly known as a &#34;composite can&#34;. However, the increasing cost of metal, relative to paperboard, has now reduced the attractiveness of this compromise. 
     It is therefore a primary object of the present invention to provide a container for fluent products, formed substantially of paperboard or like materials, which offers increased leak resistance. 
     It is another object to provide such a container which may be opened easily without the need for an opener or other implement. 
     It is yet another object to provide such a container which may be readily stacked and from which product may be poured in a precisely controlled, manner. 
     It is still another object to provide such a container which may be employed for packaging a wide variety of products while retaining a high degree of container commonality. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects as may hereinafter appear may be more clearly understood by reference to the drawings wherein: 
     FIG. 1 is a plane view of a paperboard or similar blank for the container of the present invention. 
     FIGS. 2 and 3 are perspective views showing two stages in the formation of the end closure of the present invention. 
     FIG. 4 is a perspective view showing the end closure opened and reformed as a pour spout. 
     FIG. 5 is a diametrical cross-sectional view of the container of the present invention. 
     FIG. 6 is an enlarged, fragmentary cross-sectional view of the circled area of FIG. 5. 
     FIG. 7 is a fragmentary perspective view of a portion of the container sidewall having attached thereto a rupturing member. 
     FIG. 8 is a fragmentary diametrical cross-sectional view, illustrating the container end closure in a partially opened state. 
     FIG. 9 is a fragmentary perspective view illustrating the container end closure in a partially opened state. 
    
    
     BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As best seen in FIG. 5, the composite container of the present invention comprises a rigid cylindrical sidewall 1, an end closure 2 integrally attached to the sidewall 1, a liner 3 disposed within the sidewall 1, and a cutter element 10, carried between the sidewall 1 and the liner 3, for rupturing the liner 3 to permit passage of product therethrough. 
     As shown in FIGS. 1-3, the sidewall 1 and end closure 2 may be formed from a rolled rectangular blank 4, or seamless cylinder 5, of paperboard or similar material. An edge portion 4a or 5a of the rolled blank 4 or cylinder 5, is adapted to be folded along fold lines 6 to form an interconnected series of triangular segments 7, disposed transverse the principal axis of the container (see FIG. 3) in a substantially planar configuration. 
     The triangular segments 7 comprise N large isosceles triangles 7a, N small isosceles triangles 7b, and 2N obtuse triangles 7c, where N is an even integer, preferably, but not necessarily, 6 (note: when N=6, the large isosceles triangles are equilateral). The obtuse triangles 7c flank the small isosceles triangles 7b and add thereto to form triangles congruent and opposingly interspaced with the large isosceles triangles 7a. 
     In the completed end closure 2, the triangles 7 are folded into superposed relation, with the obtuse triangles 7c lying between the large isosceles triangles 7a and the small isosceles triangles 7b. Preferably, the large isosceles triangles 7a are outermost, whereby the minimum number of folds is presented to view and larger unbroken areas are provided for printing of opening instructions or decorative matter. 
     The small isosceles triangles 7b are adhesively fastened to adjacent obtuse triangles 7c to retain the end closure 2 in a closed condition prior to opening thereof. The adhesive bonds 12 are of two types, the first type 12a being comparatively permanent, while the second type 12b is adapted for debonding to open the end closure 2. Each type of bond 12 is preferably applied to one half of the end closure 2 as best seen in FIG. 3. 
     In opening of the end closure 2, the segments 7 associated with the bonds 12b of the second type are drawn outwardly from the container by means more fully described hereinafter, to a position whereat they comprise an integral pour spout 7d coterminous with an opening in the end closure 2 (see FIG. 4). 
     A product-compatible liner 3, disposed within the sidewall 1, comprises an impervious barrier for leakproof retention of product. As best seen in FIG. 6, the peripheral edge portion 3a of the liner 3 is caught in the crimped connection 8 between the sidewall 1 and a planar, a preferably metallic, end panel 9. 
     The rupturing means comprises a cutter element 10 hingedly attached to the sidewall 1 and a flexible grasping element 11 attached to the cutter element 10 and extending through the meeting point 7e of the triangular segments 7 to the exterior of the container whereat it may be readily grasped. The grasping element 11 is also adhesively attached to one or more of the triangular elements 7 adapted to comprise a portion of the pour spout 7d. Thus, when the grasping element 11 is pulled, the triangular segments 7 associated with the second type 12b of adhesive bond are drawn outwardly, establishing an opening in the end closure 2, and forming the pour spout 7d. At the same time, the cutter element 10 is drawn against the liner 3, rupturing the same, thereby providing for the passage of product therethrough. It is to be noted that this opening procedure is accomplished by a single displacement of the grasping element 11. 
     The container as described is particularly well suited for packaging of automotive products, especially engine oil. When sold at service stations, the container may be opened, if so desired, by applying the standard combination opener and pour spout to the metal end panel 9 in the manner well known to mechanics and other auto-care professionals, or, alternatively, it may be opened in the manner described above. 
     The present container offers further advantages in that the substantial planar end closure 2 and end panel 9 allow ready stacking. 
     By selection of the proper liner material, the container may be successfully employed for packaging of a wide variety of products with a high degree of container commonality.