Treatment of Pulp Stocks Using Oxidative Enzymes to Reduce Pitch Deposition

Abstract

Methods of treating pulp stocks with an enzyme formulation containing one or more oxidative enzymes, to reduce pitch deposition, control pitch related problems, modify the physical and / or chemical properties of tri, di-, and mono-glycerides, fatty acids, resin acids, esters of fatty acids and resin acids, and metal soaps of fatty acids and resin acids, or change the concentration of triglycerides, fatty acids, resin acids, and esters of fatty acids and resin acids, have been developed. The pulp stock is treated with an enzyme formulation containing laccases, peroxidases, esterases, and / or combinations thereof. The enzyme formulations may also contain a laccase mediator and / or a dispersant. The enzyme formulation can be applied at any of several locations during the pulping and / or papermaking process. The enzyme formulation is typically applied as a solution to the pulp stock. The enzyme treatment is effective at a temperature of between about 30° C. to about 95° C., more preferably from about 50° C. to about 80° C. The pH of the pulp stock is from about 4.0 to about 7.0, more preferably from about 4.5 to 5.5. The stock can be treated for a period of time ranging from about 5 minutes to about 10 hours.

Description

FIELD OF THE INVENTION [0001] The present invention is generally in the field of treating pulp stocks with enzyme formulations in order to reduce pitch deposition. BACKGROUND OF THE INVENTION [0002] Wood resin is composed of fatty acids and resin acids, triglycerides, steryl esters, and sterols. Wood resins, as well as other extractives such as lignans, pectins, and phenols, are the major components of pitch deposits. During mechanical pulping, the encapsulated resin is liberated from ray parenchyma, cells and resin canals. Some of the dispersed resin droplets precipitate onto fiber surfaces impairing fiber to fiber bonding and thereby negatively affect the physical properties of the pulp. Dispersed resin which precipitates later in the pulping and papermaking processes can affect machine runnability and reduce paper quality which can result in increased manufacturing costs. [0003] Traditionally, pitch deposits in pulping and paper manufacturing have been reduced by debarking and se...

AI Technical Summary

Benefits of technology

[0009] Decreasing the concentration of, and / or modifying the structure of, pitch components such as fatty acids, resin acids, and esters thereof can lead to a decrease in the apparent pitch content during pulping which can result in reduced energy requirements, increased paper strength, improved paper machine runnability, and lower costs associated with paper manufacturing. Further, modification of the structure of pitch components and / or the reduction of pitch components can lead to a decrease in the need for additional chemical treatments.

Problems solved by technology

Some of the dispersed resin droplets precipitate onto fiber surfaces impairing fiber to fiber bonding and thereby negatively affect the physical properties of the pulp.

Dispersed resin which precipitates later in the pulping and papermaking processes can affect machine runnability and reduce paper quality which can result in increased manufacturing costs.

However, the use of such fixing agents has its limitations, particularly when used with recycled paper.

Such treatments, however, can result in increased concentrations of certain pitch components and by-products, such as fatty acids, which may affect machine runnability.

In fact, one of the major challenges in modern closed-cycle mills is the removal of lipophilic wood extractives that tend to accumulate in circuits.

The increasing need to recirculate water in mills is leading to an increase in pitch concentrations, which increases the chances of pitch deposition and the discharge of more heavily pitch-laden waste water.

This makes it more difficult for pulp and papermaking mills to meet state and federal requirements for reducing effluents to meet minimum effluent discharge levels.

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