Process for making abrasion resistant paper and paper and paper products made by the process

Abstract

In this papermaking process, a first strength agent is added to a stock suspension containing pulp and optionally other additives prior to its being formed into a web at the wet end of a papermaking machine. The web is then formed and processed into paper. A second strength agent is then applied to the surface of the paper. The strength agents may be selected to have opposite charge.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of provisional application Ser. No. 60 / 514279, filed Oct. 24, 2003 which is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to papermaking and, more particularly, to processes for making paper having improved properties such as abrasion resistance, decreased coefficient of friction, and increased brightness. BACKGROUND OF THE INVENTION [0003] The surface strength of manufactured paper products is receiving increased attention as papermaking technology advances and the paper products produced thereby find an ever-growing field of use. Poor surface strength has numerous repercussions on papermaking machinery and on the products themselves. Paper products having a low surface strength can bind or catch on rollers during the manufacturing process causing costly delays and waste of materials. Similarly, paper that is used as a component of a commercial product, s...

AI Technical Summary

Benefits of technology

[0014] The present invention provides a process for making paper as well as paper and paper products made by the process. In this papermaking process, a first strength agent is added to the stock suspension containing pulp and optionally other additives prior to its being formed into a web at the wet end of a papermaking machine. The web is then formed and processed into paper. A second strength agent is then applied to the surface of the paper. In this process, the strength agents are selected to have opposite charge (or to be amphoteric). Thus, in one embodiment, for example, the first strength agent is a cationic dry-strength agent and the second strength agent is an anionic dry-strength agent.

[0015] The process of this invention can be used to make paper that is resistant to abrasion. Embodiments of this process produce paper having other desirable physical properties like high optical brightness and a low friction surface. An optically bright paper can be obtained by applying the second strength agent in a solution that also contains an optical brightener. A paper having a low friction surface can be obtained by including a hydrophobic organo-silicone in the solution that is used to apply the second strength agent.

[0016] Paper made by the process is useful in a variety of paper products. In particular, the process is useful for making abrasion resistant backing paper for gypsum wallboard.

Problems solved by technology

Poor surface strength has numerous repercussions on papermaking machinery and on the products themselves.

Paper products having a low surface strength can bind or catch on rollers during the manufacturing process causing costly delays and waste of materials.

While it is known that the addition of small, hard abrasion resistant particles (also referred to as “grit”) to the paper, or to resin mixtures which coat the sheet, can enhance the abrasion resistance of papers, paper products and high-pressure laminates, their use is often accompanied by costly side effects.

However, the use of abrasion resistant particles, even microparticles or nanoparticles, tend to scratch and cause significant damage to highly polished caul plates and rollers used during the paper production process for producing both high pressure and low pressure products.

Rollers and caul plates scratched or otherwise damaged through contact with abrasion resistant materials such as described above must either be resurfaced or replaced at a significant cost