Thermo-sealing control method and packaging for resealable packaging

Abstract

A packaging and method for controlling the seal strength between two cooperating thermo-sealable films at predetermined sealing portions, where a predetermined amount of heat is applied over a predetermined period of time. The resulting packaging is resealable after the first separation of two surfaces. The strength of the seal controlled by defining the number and dimensions of a plurality of restricted areas without a material cover that is resistant to the thermo-seal effect. The restricted area can be defined with a plurality of dots of predetermined selected shapes and dimensions. The resulting article facilitates the rupture of the packaging along a predetermined path. With this process, a fixed predetermined heat and residency time can be chosen and the seal strength can still be varied in different areas of a packaging. Non-sealable microdots with a predetermined amount of adhesive deposits also covered by a polypropylene powder deposit permit its resealing.

What is claimed is: 
     
         1 . A process for controlling the seal strength between two cooperating thermo-sealable films comprising the steps of:
 A) defining at least one sealing portion of two cooperating thermo-sealable surfaces of two respective films, one of said surfaces being partially covered with material having predetermined thermal insulation characteristics thereby resulting in a selectively defined plurality of non-sealable areas with a controlled predetermined thermal seal strength in said non-sealable areas, thereby providing a path having less resistance to disengagement of the seal between the two films within said at least one sealing portion;   B) depositing an effective amount of an adhesive on a predetermined number of said non-sealable areas;   C) electrostatically depositing polypropylene powder over said non-sealable areas where said adhesive was deposited; and   D) applying a predetermined amount of heat to said sealing portions over a predetermined time period to achieve an effective seal where there are no non-sealable areas on said surfaces.   
     
     
         2 . The process set forth in  claim 1  wherein said non-sealable areas are defined by dots having predetermined shapes and dimensions. 
     
     
         3 . The process set forth in  claim 2  wherein the shape of said dots is circular. 
     
     
         4 . The process set forth in  claim 3  wherein the shape of said dots is varied to achieve a predetermined seal strength. 
     
     
         5 . The process set forth in  claim 4  wherein the dimensions of said dots are varied to achieve a predetermined seal strength. 
     
     
         6 . The process set forth in  claim 5  wherein the density of said dots is varied to achieve a predetermined seal strength. 
     
     
         7 . The process set forth in  claim 6  wherein the friction coefficient of said material falls within a predetermined range that is compatible with high-speed production methods for packaging products. 
     
     
         8 . The process set forth in  claim 1  wherein said step of depositing an effective amount of an adhesive on a predetermined number of non-sealable areas utilizes a rotogravure process. 
     
     
         9 . A packaging for products including at least one seal portion using the method set forth in  claim 1 . 
     
     
         10 . A packaging for products including at least one seal portion using the method set forth in  claim 2 . 
     
     
         11 . A packaging for products including at least one seal portion using the method set forth in  claim 3 . 
     
     
         12 . A packaging for products including at least one seal portion using the method set forth in  claim 4 . 
     
     
         13 . A packaging for products including at least one seal portion using the method set forth in  claim 5 . 
     
     
         14 . A packaging for products including at least one seal portion using the method set forth in  claim 6 . 
     
     
         15 . A packaging for products including at least one seal portion using the method set forth in  claim 7 . 
     
     
         16 . A packaging for products including at least one seal portion using the method set forth in  claim 8 . 
     
     
         17 . A packaging for products including at least one sealing portion formed with two cooperating thermo-sealable surfaces of two respective films, one of said surfaces being partially covered in discrete separate areas with a material having predetermined thermal insulation characteristics thereby resulting in a selectively defined plurality of non-sealable areas, with a controlled predetermined thermal seal strength in said non-sealable areas when a predetermined amount of heat is applied over a predetermined time period and a predetermined number of said non-sealable areas include a predetermined amount of a cooperating adhesive deposited thereon covered by an electrostatic deposit of polypropylene powder that binds with said other surface upon the application of said heat. 
     
     
         18 . The packaging set forth in  claim 17  wherein said restricted areas are defined by dots having predetermined shapes and dimensions. 
     
     
         19 . The packaging set forth in  claim 18  wherein the shape of said dots is circular. 
     
     
         20 . The packaging set forth in  claim 19  wherein the shape of said dots is varied to achieve a predetermined seal strength. 
     
     
         21 . The process set forth in  claim 20  wherein the dimensions of said dots are varied to achieve a predetermined seal strength. 
     
     
         22 . The process set forth in  claim 21  wherein the density of said dots is varied to achieve a predetermined seal strength. 
     
     
         23 . The packaging set forth in  claim 22  wherein the friction coefficient of said material falls within a predetermined range that is compatible with high-speed production methods for packaging products. 
     
     
         24 . The packaging set forth in  claim 23  wherein said adhesive is deposited using a rotogravure process.