Flat container comprising thermoplastic resin and method for molding the same

Abstract

The invention realizes easy manufacturing of a flat container molded by blow molding, in which the wall thickness of a container wall is made uniform, and which provides improved mechanical strength, heat resistance, etc. and has a good appearance. The flat container obtained by the blow molding of a polyester resin is characterized in that the container has a flatness ratio of not less than 1.3, and in that its body has a wall thickness ratio of a maximum wall thickness to a minimum wall thickness of not more than 1.6, a difference in elongation between a maximally stretched portion and a minimally stretched portion of not more than 150% in a tensile test at 95° C., a crystallinity of not less than 30%, and a difference in TMA non-load change between a maximally stretched portion and a minimally stretched portion of not more than 500 μm at 75° C. and 100° C.

What is claimed is: 
     
         1 . A flat polyester resin container, comprising a polyester resin, the container being obtained by blow molding the polyester resin,
 wherein the flatness ratio, which is the ratio of a major axis to a minor axis of a cross section parallel to the bottom of the container, is not less than 1.3 to 2.5,   the flat polyester resin container is a heat resistant container,   the wall thickness ratio of a maximum wall thickness to a minimum wall thickness of a body of the container is not more than 1.6,   a difference in elongation between a maximally stretched portion and a minimally stretched portion of the body of the container in a tensile test at 95° C. is not more than 150%,   the crystallinity of the body of the container is not less than 30%, and   a difference in TMA non-load change between a maximally stretched portion and a minimally stretched portion of the body of the container at 75° C. and 100° C. is not more than 500 μm.   
     
     
         2 . The flat polyester resin container according to  claim 1 , wherein the sectional shape of the body of the flat container is a rectangle or an ellipse. 
     
     
         3 . The flat polyester resin container according to  claim 1 , wherein the polyester resin is polyethylene terephthalate. 
     
     
         4 . The flat polyester resin container according to  claim 1 , wherein the flat container is of a multilayer structure comprising a polyester resin layer and a functional thermoplastic resin layer. 
     
     
         5 . The flat polyester resin container according to  claim 1 , wherein one or more transverse ribs are provided in a horizontal concavity on a long-side side surface.