Formed Thermoplastic Article Having a Smoothly-Curved Distal Periphery

Abstract

The disclosure relates to forming shaped thermoplastic articles having smooth peripheries. Many thermoplastic articles have sharp edges formed upon molding or cutting the article from a feedstock sheet. Such sharp edges can damage thin plastic films or flesh which they contact, and smoothing the edges is desirable. Described herein are methods of forming a smooth periphery for such sharp-edged articles by rolling over the sharp edge. The smoothing operation is performed by forming a deflectable flange including a bend region separated from the potentially sharp peripheral edge by a spacer, deflecting a portion of the deflectable flange, and softening at least one bent portion of the deflectable flange to yield a smooth periphery upon cooling. A liner sheet may be attached to the feedstock sheet prior to, during, or after forming and can be peelable therefrom.

1 - 142 . (canceled) 
     
     
         143 . A rounded rectangular tray comprising a shaped thermoplastic substrate sheet, the shape of the substrate sheet including
 a concave, tray-shaped body and   a rim adjoining the body about its entire periphery, the rim having a smooth periphery and comprising
 a substantially planar extension which adjoins the body at a proximal extent of the extension and extends peripherally away from the body to a distal extent of the extension, 
 a smoothly-curved bend region adjoining the distal extent of the extension and connecting thereto a bent portion which carries the peripheral edge of the sheet positioned away from the periphery of the tray, 
 at least one of the bend region and the bent portion defining the smooth peripheral edge of the tray. 
   
     
     
         144 . The tray of  claim 143 , wherein the thermoplastic is selected from the group consisting of polyethylenes, polypropylenes, polyethylene terephthalates, and polyvinyl chlorides. 
     
     
         145 . The tray of  claim 143 , wherein the thermoplastic is a polyethylene terephthalate. 
     
     
         146 . The tray of  claim 143 , wherein the depth of the concavity of the tray being at least several centimeters. 
     
     
         147 . The tray of  claim 143 , wherein the tray includes ribs on the sidewalls of the concavity. 
     
     
         148 . The tray of  claim 143 , wherein the sheet is substantially optically clear. 
     
     
         149 . The tray of  claim 148 , wherein the sheet is substantially optically clear at substantially all parts of the tray. 
     
     
         150 . The tray of  claim 143 , wherein the ratio d/D is at least ½, wherein d is the dimension of the nearest approach of the peripheral edge of the sheet to the body and D is the distance from the body of the peripheral-most extent of the rim of the container. 
     
     
         151 . The tray of  claim 143 , wherein the ratio d/D is not greater than ¼, wherein d is the dimension of the nearest approach of the peripheral edge of the sheet to the body and D is the distance from the body of the peripheral-most extent of the rim of the container. 
     
     
         152 . The tray of  claim 143 , wherein the ratio d/D is not less than ¾, wherein d is the dimension of the nearest approach of the peripheral edge of the sheet to the body and D is the distance from the body of the peripheral-most extent of the rim of the container. 
     
     
         153 . The tray of  claim 143 , wherein a substantially flat spacer is connected with the bent portion and carries the peripheral edge of the sheet. 
     
     
         154 . The tray of  claim 153 , wherein the combined curvatures of the bend region and the bent portion cause the spacer to be rotationally displaced from the plane of the extension by an offset angle of at least 120 degrees. 
     
     
         155 . The tray of  claim 153 , wherein the combined curvatures of the bend region and the bent portion cause the spacer to be rotationally displaced from the plane of the extension by an offset angle of at least 135 degrees. 
     
     
         156 . The tray of  claim 153 , wherein the combined curvatures of the bend region and the bent portion cause the spacer to be rotationally displaced from the plane of the extension by an offset angle of at least 180 degrees. 
     
     
         157 . The tray of  claim 153 , wherein the combined curvatures of the bend region and the bent portion cause the spacer to be rotationally displaced from the plane of the extension by an offset angle of at least 270 degrees. 
     
     
         158 . The tray of  claim 153 , wherein the spacer is positioned approximately parallel to the plane of the extension. 
     
     
         159 . The tray of  claim 158 , wherein the body includes a substantially flat bottom surrounded by sidewalls, the plane of the extension being substantially parallel to the bottom. 
     
     
         160 . The tray of  claim 159 , wherein rim includes a stacking extension at which the bent portion extends farther away from the extension than the bent portion extends away from the extension at other locations, whereby the stacking extension inhibits nesting of the tray snugly within a second identical tray. 
     
     
         161 . The tray of  claim 160 , wherein the rim includes a stacking extension at each of its four corners. 
     
     
         162 . The tray of  claim 159 , wherein the body includes at least one outwardly-extending stacking lug to inhibit nesting of the tray snugly within a second identical tray. 
     
     
         163 . The tray of  claim 162 , wherein the body includes an outwardly-extending stacking lug at each of its four corners. 
     
     
         164 . The tray of  claim 159 , wherein the spacer includes a substantial peripheral flange which bears the peripheral edge of the sheet, the peripheral flange being connected to the spacer by way of an elbow which defines a peripheral flange angle F between the peripheral flange and the spacer 
     
     
         165 . The tray of  claim 164 , wherein the magnitude of angle F is not more than about 90 degrees. 
     
     
         166 . The tray of  claim 165 , wherein the magnitude of angle F is near 0 degrees, such that the peripheral flange, the elbow, and the spacer form a hook-like structure. 
     
     
         167 . The tray of  claim 164 , wherein the magnitude of angle F is between 90 and 180 degrees. 
     
     
         168 . The tray of  claim 167 , wherein the magnitude of angle F is near 180 degrees, such that the peripheral flange, the elbow, and the spacer form a structure wherein the peripheral flange is nearly indistinguishable from the spacer. 
     
     
         169 . The tray of  claim 164 , wherein the peripheral flange is substantially flat and the offset angle between the extension and the peripheral flange is at least about 90 degrees. 
     
     
         170 . The tray of  claim 143 , wherein a substantially flat spacer is interposed between the bend region and the bent portion. 
     
     
         171 . The tray of  claim 170 , wherein the curvature of the bend region causes the spacer to be rotationally displaced from the plane of the extension by an offset angle of about 90 degrees. 
     
     
         172 . The tray of  claim 171 , wherein the offset angle is from 85-105 degrees.