Abstract:
A method of producing random and irregular markings and impressions on synthetic cork stoppers so as to closely mimic the surface texture of natural cork, and the stoppers produced thereby. In one embodiment, the stopper is produced in a mold featuring a textured inner surface. In another embodiment, the stopper is extruded.

Description:
[0001]     This application claims priority from U.S. provisional application No. 60/751,299. 
     
    
     FIELD OF INVENTION  
       [0002]     This invention relates to the field of container closures commonly utilizing natural or basic synthetic cork.  
       BACKGROUND OF THE INVENTION  
       [0003]     Producers of wine and other products that are sold in bottles or other containers that are traditionally closed and sealed with cork stoppers have long been concerned about contamination of the cork, which can lead to spoilage of the product within the container. In the case of wine or olive oil, for example, such spoilage is immediately noticeable by the consumer and renders the product unfit for consumption.  
         [0004]     For that reason, there has been a movement in recent times toward the use of synthetic stoppers in place of cork. The material used in the synthetic stopper will depend on the characteristics of the container&#39;s contents. If the synthetic materials used are non-reactive with the contents of the container, the synthetic stopper is a complete solution to the problem of contamination of the cork, and consequently the contents of the container.  
         [0005]     However, penetration of synthetic stoppers into the food and wine container industry has been slow. Many producers of food and wine are reluctant to switch from traditional corks to synthetic stoppers for purely aesthetic reasons. Cork has a distinctive color and appearance in that it is rarely smooth, but rather is pockmarked with dark spots and often covered with pits and small voids in the surface of cut cork. Synthetic cork products have been produced to approximate the color, but not the physical appearance, of natural cork. Attempts have been made to create a synthetic stopper that realistically imitates natural cork. U.S. Pat. No. 4,363,849 (Paisley et al.) discloses an injection molding process wherein “coils” of synthetic material are injected into a mold; the boundaries between the “coils” create random lines in the stopper surface. U.S. Pat. No. 4,507,405 (Paisley et al.) discloses that these coils may be injected along with a colorant to accentuate the boundary lines. U.S. Pat. No. 4,522,856 (Paisley et al.) discloses a method of coloring the synthetic stopper to appear more like natural cork. However, these references disclose only methods of effectively “drawing” a cork-like appearance on the stopper surface in two dimensions. In order to gain wider acceptance, a need exists for synthetic stoppers with textured surfaces that appear more like the natural cork to which people are accustomed.  
       SUMMARY OF INVENTION  
       [0006]     In order to more accurately simulate the appearance of natural cork, the appearance of the exterior surface of the synthetic stopper should feature random and irregular holes, markings, or dimples. The surface may also feature color variations as found in natural cork. Viewed broadly, the invention provides a method of producing random and irregular holes, markings, and dimples on the surface of a synthetic stopper. The invention includes, in another aspect, the stopper made to appear as if it was formed of natural cork. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a side elevation view of a stopper made by a method in accordance with an exemplary embodiment of the present invention.  
         [0008]      FIG. 2  is a plan view of a mold for making a stopper by a method in accordance with an exemplary embodiment of the present invention.  
         [0009]      FIG. 3  is a side elevation view of a possible embodiment of an extrusion apparatus for making a stopper by a method in accordance with an exemplary embodiment of the present invention.  
         [0010]      FIG. 4  is a front section view along Line  4  of the apparatus shown in  FIG. 3 .  
         [0011]      FIG. 5  is a side elevation view of a second possible embodiment of an extrusion apparatus for making a stopper by a method in accordance with an exemplary embodiment of the present invention.  
         [0012]      FIG. 6  is a front section view along Line  6  of the apparatus shown in  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0013]     Methods of creating the random and irregular markings of the present invention include molding the details directly into the surface of the stopper and extruding the synthetic material into a desired shape before passing it through forming cylinders or rollers that contain the negative of the desired surface texture, and which imprint the texture onto the material&#39;s exterior surface.  
         [0014]      FIG. 1  shows a side elevation view of a stopper  10  made by a method in accordance with an exemplary embodiment of the present invention. Stopper  10  features random and irregular holes, markings, and dimples  12  on its outer surface. It will be obvious to one of ordinary skill in the art that the exact outer shape of stopper  10  is not limited to the shape depicted in  FIG. 1 ; a number of methods of shaping a stopper are well-known in the art. Accordingly, the shape depicted in  FIG. 1  should not be construed as limiting the present invention.  
         [0015]      FIG. 2  shows a mold  14  used in a method in accordance with an exemplary embodiment of the present invention. Mold  14  includes interior surface  16 , which features randomly-placed and irregularly-shaped contours, bumps, and ridges  18 . When a suitable soft synthetic material is introduced into mold  14  and the mold is closed, bumps and ridges  18  create markings and dimples  12  in the outer surface of the synthetic material. As the material hardens, markings and dimples  12  become permanently impressed in the outer surface of the material, forming stopper  10 . Though  FIG. 2  depicts a mold for a single stopper according to the invention, it will be understood that such molds could be arranged in large groups to be filled and cooled simultaneously for mass production of the stoppers, or, alternatively, could have a one-piece construction.  
         [0016]      FIGS. 3-6  depict exemplary embodiments of an alternative method of the invention. In  FIG. 3 , synthetic material  20  is extruded through extrusion tube  22 . Material  20  exits tube  22  with a smooth outer surface, and proceeds through impressing rollers  24 . Rollers  24  are preferably shaped so as to contact substantially all of the outer surface of material  20 , and feature on their contacting surfaces ridges and bumps  26 . The ridges and bumps  26  create impressions and markings  12  in the exterior surface of the material  20 . As depicted, material  20  may be cut into individual stoppers  10  either before or preferably after the impressing step by cutting means  28 .  FIG. 4  depicts the rollers  24  of  FIG. 3  as seen along the direction of Line  4 . Depending on the nature of the chosen material, cooling means (not shown) may be employed in the process to ensure that the impressions and markings are rendered permanent on the material surface.  
         [0017]      FIGS. 5-6  depict an alternative exemplary embodiment of the extrusion process shown in  FIGS. 3-4 . In  FIG. 5 , rollers  24  are integral with tube  22 .  FIG. 6  shows a view of the apparatus of  FIG. 5  along Line  6 .  
         [0018]     It should be clear to persons skilled in the art that the cross-sectional shape of material  20  (and thus stopper  10 ) is not limited to a circle, and that rollers  24  may likewise be shaped to conform to the desired final cross-sectional shape of stopper  10 . Although molding and extrusion are discussed herein, other methods of forming synthetic stoppers are known in the art. Likewise, while the impressing step is preferably performed by rollers, it may also be performed by other means; as used in this invention, “impressing” includes 3-dimensional detailing of the stopper surface by any means. The desired impressions could be stamped into the extruded soft synthetic material by stamps preferably shaped so as to contact substantially all of the material&#39;s exterior surface. The impressions could be cut by blades into the surface of the material, either before or after it hardens. The material also may be routed through the impressing step in any orientation, and need not be processed individually. For example, individual stoppers could be arranged in a layer, and impressed in batches.  
         [0019]     Synthetic material suitable for use in stoppers is well-known in the art. Suitable materials include hot resin in either compact form or expanded via foaming/expanding agents. The guiding characteristics for selecting a material are non-reactivity with the expected container contents and softness, determined by compressibility and recuperation. Roughness is not necessarily a limitation, as it will depend on the individual application. Any color may be used, but will preferably mimic natural cork. The color also may or may not include dark points as found in natural cork.  
         [0020]     The preferred embodiments of the present invention are used to store wine; however, use of the stoppers as described is not limited to wine, or even food; the stoppers may be used any container where use of a compressible, non-reactive stopper is desirable.