Low density paperboard articles
View Patent ↗The invention provides a low density paperboard material for use in producing an insulated container, and is especially well-suited for making cups. The paperboard material comprises a paperboard web including wood fibers and expanded microspheres, and has a relatively low density ranging from about 6 to about 10 lb/3MSF/mil, a relatively high caliper ranging from about 24 to about 35 mil, and an internal bond strength of at least about 80×10 −3 ft-lb f preferably at least 100×10 −3 ft-lb f . For applications such as cups the material is also coated on one or both sides with a barrier coating, preferably low density polyethylene, to limit liquid penetration into the web. The low density paperboard material of the invention is convertible for manufacture of containers, particularly cups, and the surface of the low density board may have a Sheffield smoothness of 300 SU or greater.
1. An assembled paper container which comprises a sidewall and a bottom sealably joined together wherein the sidewall is provided by a paperboard material which comprises a paperboard web including wood fiber and from about 5 to about 10 wt. % dry basis expanded synthetic polymer microspheres based on the total weight of the web dispersed within the fibers, an apparent density of from about 6.0 to about 10 lb/3MSF/mil, a caliper of from about 24 to about 35 mil, an average internal bond of at least about 80×10 −3 ft-lbf, a Sheffield smoothness of about 300 SU or greater, and a barrier coating having a thickness of from about 0.5 to about 3.5 mil disposed adjacent at least one surface of the web.
2. An assembled paper cup which comprises a sidewall and a bottom sealably joined together wherein the sidewall is provided by a paperboard material which comprises a paperboard web including wood fiber and from about 5 to about 10 wt. % dry basis expanded synthetic polymer microspheres based on the total weight of the web dispersed within the fibers, an apparent density of from about 6.0 to about 10 lb/3MSF/mil, a caliper of from about 24 to about 35 mil, an average internal bond of at least about 80×10 −3 ft-lbf, a Sheffield smoothness of about 300 SU or greater, and a barrier coating having a thickness of from about 0.5 to about 3.5 mil disposed adjacent at least one surface of the web.