Low density paperboard sheet and tube incorporating the same

Abstract

The present invention provides a low-density paperboard sheet of at least one paperboard layer made from a stock solution that includes a proportion of standard wood flour or fine sawdust in addition to traditional cellulose fibers. The proportion of sawdust can range from 1% to 40% by weight. Advantageously the sawdust of the present invention does not require a costly refining or micronization operation in order to produce low-density, high yield paperboard layers. Additionally, the low-density layers of the present invention may be readily combined with other layers of varying densities in order to tailor the physical properties of the resulting multi-layer sheet to a given application.

Description

FIELD OF THE INVENTION [0001] The invention relates to paperboard sheets, a process for making them, and to paperboard tubes made from such sheets. BACKGROUND OF THE INVENTION [0002] Paperboard is used in a wide variety of applications throughout numerous industries. For example, paperboard sheets are used as slip sheets for separating products, as a backing for laminates and as floor mats. Paperboard is also used to make partitions and roofing felt as needed for the construction of residential and commercial buildings. Additionally, paperboard sheet material can be wound into tubes and used as winding cores for winding filamentary materials such as yams and threads, or for winding continuous sheet materials such as paper, plastic film, and metal foils or sheets. Such tubes can also be used to make containers for food products such as frozen juices, bread dough and snack products. Paperboard tubes are used as forms in the construction industry, e.g., for molding concrete columns and...

AI Technical Summary

Benefits of technology

The present invention provides a low-density paperboard sheet made from a stock that includes a proportion of standard wood flour or fine sawdust in addition to traditional cellulose fibers. The sawdust does not require a costly refining or micronization operation to produce low-density, high-yield paperboard sheets. The fine sawdust is readily produced by thin curf band saw blades and can be easily removed from excessively large pieces of wood. The low-density paperboard of the present invention can be produced using standard papermaking machines and can be layered to achieve different densities. The paperboard sheets can be converted into partitions, support posts, slip sheets, floor mats, or the like which serve to protect delicate objects from damage. The paperboard tubes can be used as winding cores for plastic film or other similar elastic products.

Problems solved by technology

Low-density sheets however, tend to be weaker, more compressible or sponge-like and thus capable of greater absorption.

Secondary operations, such as the micronization process described above, add additional and often prohibitive costs to papermaking.