Apparatus and method for resisting tear propagation in polymeric products

Abstract

A plastic bag for holding materials comprising at least one polymeric panel defining the outer walls of the plastic bag. The at least one polymeric panel is interconnected to form a substantially cylindrical shape. The at least one polymeric panel defines a machine direction and a cross direction perpendicular to the machine direction. A plurality of substantially parallel rows on the at least one polymeric panel wherein the plurality of substantially parallel rows is comprised of a plurality of curvilinear areas. The plurality of curvilinear areas having a protrusion or an indentation in the at least one polymeric panel. The bag further comprises a plurality of substantially parallel neutral areas wherein each substantially parallel neutral area is defined by an area between two adjacent rows in the plurality of substantially parallel rows.

1 . A plastic bag for holding trash, debris and/or other materials comprising:
 at least one polymeric panel defining the outer walls of the plastic bag, the at least one polymeric panel interconnected to form a substantially cylindrical shape, a first end of the substantially cylindrical shape sealed to form a bottom of the plastic bag and a second end forming an opening of the plastic bag, the at least one polymeric panel defining a machine direction and a cross direction perpendicular to the machine direction;   a plurality of substantially parallel rows on the at least one polymeric panel, the plurality of substantially parallel rows comprised of a plurality of curvilinear areas wherein each of the plurality of curvilinear areas is a protrusion or an indentation in the at least one polymeric panel;   wherein each of the plurality of substantially parallel rows extends in the cross direction of the at least one polymeric panel.   
   
   
       2 . The plastic bag of  claim 1  further comprising a plurality of substantially parallel neutral areas, each substantially parallel neutral area defined by an area between two adjacent rows in the plurality of substantially parallel rows 
   
   
       3 . The plastic bag of  claim 1  wherein the plurality of curvilinear areas are elliptical. 
   
   
       4 . The plastic bag of  claim 1  wherein the plurality of curvilinear areas are S-shaped. 
   
   
       5 . The plastic bag of  claim 1  wherein the plurality of curvilinear areas are a series of alternating protrusions and indentations. 
   
   
       6 . The plastic bag of  claim 1  wherein the plurality of curvilinear areas are substantially uniform in size and depth. 
   
   
       7 . The plastic bag of  claim 1  wherein the plurality of curvilinear areas and plurality of substantially parallel neutral areas are not visually distinct. 
   
   
       8 . A plastic sheet with increased resistance to tear propagation comprising:
 a plastic sheet having an upper surface, a lower surface, and a plurality of edges, wherein the plastic sheet has an ordinary elasticity and the plastic sheet defines a machine direction and a cross direction perpendicular to the machine direction;   a plurality of substantially parallel rows defined on the plastic sheet, the plurality of substantially parallel rows traversing the plastic sheet generally in the cross direction, the plurality of substantially parallel rows comprised of a plurality of curvilinear areas wherein each of the plurality of curvilinear areas is a protrusion or an indentation in the plastic sheet   
   
   
       9 . The plastic sheet of  claim 8  further comprising a plurality of substantially parallel neutral areas, each substantially parallel neutral area defined by an area between two adjacent rows in the plurality of substantially parallel rows. 
   
   
       10 . The plastic sheet of  claim 8  wherein the plurality of curvilinear areas are elliptical. 
   
   
       11 . The plastic sheet of  claim 8  wherein the plurality of curvilinear areas are S-shaped. 
   
   
       12 . The plastic sheet of  claim 8  wherein the plurality of curvilinear areas and plurality of substantially parallel neutral areas are not visually distinct. 
   
   
       13 . A method of manufacturing plastic film having increased resistance to tear propagation comprising the steps of:
 providing a blown-film polymeric tube, a machine direction defined by the longitudinal axis of the blown-film polymeric tube and a cross direction defined by an axis perpendicular to the longitudinal axis of the blown-film polymeric tube;   flattening the blown-film polymeric tube;   embossing the blown-film polymeric tube with a plurality of curvilinear areas, each curvilinear area being either a protrusion or an indentation;   
   
   
       14 . The method of  claim 13  wherein the plurality of curvilinear areas are arranged into a plurality of substantially parallel rows extending in the cross direction of the blown-film polymeric tube. 
   
   
       15 . The method of  claim 14 , wherein the plurality of substantially parallel rows further define a plurality of substantially parallel neutral areas, each substantially parallel neutral area defined by an area between two adjacent rows in the plurality of substantially parallel rows. 
   
   
       16 . The method of  claim 13 , further comprises the steps of forming a plurality of plastic bags from the blown-film polymeric tube. 
   
   
       17 . The method of  claim 13 , wherein embossing the blown-film polymeric tube comprises the step of passing the blown-film polymeric tube through a pair of complementary embossing rollers. 
   
   
       18 . The method of  claim 13 , further comprising the step of:
 redirecting a tear propagating through the blown-film polymeric tube when the tear encounters one of the plurality of curvilinear areas.