Hollow plastic article

A hollow article for use as a beverage cup, or as a container, the hollow article having an annular sidewall and a base wall defining a central hollow cavity, the annular sidewall having a top rim and a bottom end, the annular sidewall comprising a sandwich structure of plastic material having inner and outer skins and an integral expanded cellular foam layer therebetween, wherein at least a portion of the annular sidewall has an inner surface of the inner skin inclined at a first acute angle to a longitudinal axis of the hollow article and an opposite outer surface of the outer skin inclined at a second acute angle to the longitudinal axis of the hollow article, wherein the second acute angle is greater than the first acute angle, wherein the at least a portion of the annular sidewall has a thickness at an upper end of the sandwich structure which is greater than a thickness at a lower end of the sandwich structure, wherein the first and second acute angles are each within a range of from 5 to 8 degrees and the second acute angle is from 0.1 to 1 degrees higher than the first acute angle, wherein the upper end of the sandwich structure is below the top rim and the lower end of the sandwich structure is at the bottom end of the annular sidewall.

A hollow article for use as a beverage cup, or as a container, the hollow article having an annular sidewall and a base wall defining a central hollow cavity, the annular sidewall having a top rim and a bottom end, the annular sidewall comprising a sandwich structure of plastic material having inner and outer skins and an integral expanded cellular foam layer therebetween, wherein the integral expanded cellular foam layer between the inner and outer skins has a density which is from 27.5 to 45% of a density of the inner and outer skins, wherein at least a portion of the annular sidewall has an inner surface of the inner skin inclined at a first acute angle to a longitudinal axis of the hollow article and an opposite outer surface of the outer skin inclined at a second acute angle to the longitudinal axis of the hollow article, wherein the second acute angle is greater than the first acute angle, wherein the at least a portion of the annular sidewall has a thickness at an upper end of the sandwich structure which is greater than a thickness at a lower end of the sandwich structure, and wherein the opposite outer surface of the outer skin is undulating in a direction extending at least partly around the longitudinal axis of the hollow article.