Formed Thermoplastic Article Having Smooth Edges

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.

1 - 2 . (canceled) 
     
     
         3 . The article of  claim 52 , wherein the bend region interconnects the spacer with the extension at an angle not less than 75 degrees, but less than 105 degrees. 
     
     
         4 . The article of  claim 52 , wherein the bend region interconnects the spacer with the extension at an angle of about 87-93 degrees. 
     
     
         5 . The article of  claim 52 , wherein the bend region interconnects the spacer with the extension at an angle of about 90-93 degrees. 
     
     
         6 - 8 . (canceled) 
     
     
         9 . The article of  claim 52 , wherein the body has a concave compartment with an opening and the smooth bend region about the entire periphery of the opening. 
     
     
         10 . The article of  claim 9 , further comprising a film that contacts the smooth periphery of the body about the entire periphery of the opening. 
     
     
         11 . The article of  claim 10 , wherein the film over-wraps the body and the film is sealed to itself to envelop the body. 
     
     
         12 . The article of  claim 11 , wherein the film extends across the opening of the compartment and is sealed about the periphery of the opening. 
     
     
         13 - 15 . (canceled) 
     
     
         16 . The article of  claim 9 , wherein the extension extends laterally in a plane about the periphery of the opening and wherein the spacer and the interior of the compartment and the spacer are disposed on the same side of the plane. 
     
     
         17 - 26 . (canceled) 
     
     
         27 . The article of  claim 52 , wherein the spacer includes a peripheral flange at the peripheral edge of the deflectable flange and an elbow connecting the peripheral flange to the remainder of the spacer at an angle other than 180 degrees. 
     
     
         28 - 43 . (canceled) 
     
     
         44 . The article of  claim 52 , wherein the spacer is rolled-over sufficiently that the peripheral edge is turned at least about 180 degrees relative to the extension. 
     
     
         45 . The article of  claim 52 , wherein the rolled-over spacer has a J-shaped conformation. 
     
     
         46 . The article of  claim 52 , wherein the rolled-over spacer has a U-shaped conformation. 
     
     
         47 - 48 . (canceled) 
     
     
         49 . A method of making a container having a concave compartment and a smooth periphery, the method comprising
 forming a thermoplastic sheet into a shape comprising a body including the concave compartment and a deflectable flange surrounding the compartment at the periphery of the body, the periphery being formed by cutting the shape from the sheet to form the peripheral edge of the shape,
 the deflectable flange comprising a spacer bearing the peripheral edge, the spacer being connected to the body by way of an extension that extends peripherally away from the body and a bend region interconnecting the spacer and the extension, 
 the spacer including a peripheral flange which includes the peripheral edge and an elbow that connects the peripheral flange to the remainder of the spacer at an angle other than 180 degrees, 
 the bend region having a smooth contour and interconnecting the spacer at an approximately right angle with the extension; 
   impinging a ram against the spacer to deflect the spacer toward the extension, whereby the magnitude of the angle between the spacer and the extension is decreased on account of at least one portion of the deflectable flange becoming bent, relative to its pre-impingement position, the bent portion being selected from the group consisting of the extension, the bend region, and the spacer;   heating the bent portion to at least the glass transition temperature of the thermoplastic;   cooling the bent portion below the glass transition temperature, whereby the bent portion remains deflected from its pre-impingement position even upon discontinuation of the impingement; and   disengaging the ram from the spacer to yield the body with a smooth periphery.   
     
     
         50 . A method of forming a smooth periphery on a thermoformed article that is made from a thermoplastic and that has a sharp peripheral edge, the method comprising
 forming a deflectable flange about the peripheral edge of the article,
 the deflectable flange comprising a spacer including peripheral edge of the article, the spacer being connected to the article by way of an extension that extends peripherally away from the article and a bend region interconnecting the spacer and the extension, 
 the bend region having a smooth contour and interconnecting the spacer at an approximately right angle with the extension; 
   impinging a ram against the spacer to deflect the spacer toward the extension, whereby the magnitude of the angle between the spacer and the extension is decreased on account of at least one portion of the deflectable flange becoming bent, relative to its pre-impingement position, the bent portion being selected from the group consisting of the extension, the bend region, and the spacer;   heating the bent portion to at least the glass transition temperature of the thermoplastic;   cooling the bent portion below the glass transition temperature, whereby the bent portion remains deflected from its pre-impingement position even upon discontinuation of the impingement; and   disengaging the ram from the spacer to yield the article with a smooth periphery.   
     
     
         51 . (canceled) 
     
     
         52 . A thermoformed article having a smooth periphery, the article comprising a body made from a thermoplastic and having a smooth bend region connected to the periphery of the body by an extension of the thermoplastic, the bend region connecting the extension with a spacer bearing the peripheral edge of the thermoplastic at a position peripheral to the bend region, and a spacer having a rolled-over conformation that is bent toward the extension, with the peripheral edge turned away from the periphery of the article. 
     
     
         53 . The article of  claim 52 , wherein the peripheral edge is turned under the spacer sufficiently that the peripheral edge is not directly viewable from the exterior of the article. 
     
     
         54 . The article of  claim 52 , wherein the peripheral edge is turned under the spacer sufficiently that the peripheral edge is disposed sufficiently away from the perimeter of the article that the article is suitable for sealing with a thin plastic film by any of OW, VSP, MAP technologies. 
     
     
         55 . The article of  claim 52 , wherein the body has the shape of a rounded rectangular tray having a concave compartment formed therein, the extension encircling the periphery of the compartment. 
     
     
         56 . The article of  claim 55 , wherein the compartment is configured such that a plurality of the article are stackable in a nested conformation. 
     
     
         57 . A system for making a shaped article having a body with a smooth periphery, the system comprising
 a thermoformer, including at least one mold for forming a thermoplastic sheet into a shape comprising the body and a deflectable flange about the periphery of the body,
 the deflectable flange comprising a spacer bearing the peripheral edge of the thermoplastic, the spacer being connected to the body by way of an extension that extends peripherally away from the body and a bend region interconnecting the spacer and the extension, 
 the spacer including a peripheral flange which includes the peripheral edge and an elbow that connects the peripheral flange to the remainder of the spacer at an angle other than 180 degrees, 
 the bend region having a smooth contour and interconnecting the spacer at an approximately right angle with the extension; 
   a ram operably connected with the thermoformer for impinging the ram against the spacer to deflect the spacer toward the extension, whereby the magnitude of the angle between the spacer and the extension is decreased on account of at least one portion of the deflectable flange becoming bent, relative to its pre-impingement position, the bent portion being selected from the group consisting of the extension, the bend region, and the spacer; and   a heater for heating the bent portion to at least the glass transition temperature of the thermoplastic.   
     
     
         58 - 59 . (canceled)