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

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

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.

Traditionally, pitch deposits in pulping and paper manufacturing have been reduced by debarking and seasoning logs and wood chips aid by the use of physiochemical control agents. For example, cationic coagulant chemicals have been used to fix the extractives to the fibers so that the pitch deposits can be removed. However, the use of such fixing agents has its limitations, particularly when used with recycled paper.

In order to overcome the limitations associated with the use of physiochemical treatments, biological treatments, particularly the use of enzymes, have been developed for pitch control. For example, lipases have been used to degrade triglycerides into glycerol and fatty acids to reduce the pitch deposition problems caused by triglycerides. 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.

Laccase has been used in some cases to treat pulp, for example, with suitable amounts of manganese peroxidase enzyme, hydrogen perioxidase and Mn(II) ions or with laccase enzyme at an acid pH for between 30 and 240 minutes at a temperature between 25 and 60° C., as described in U.S. Pat. No. 5,691,193; at a dose of between 0.1 and 100 IU of oxidoreductase are employed per gram of lignin-containing material (dry weight) with between 1 and 500 mmol mediator/kg, of pulp, as described in U.S. Pat. No. 6,242,245; 0.01 to 100 mg enzyme protein per kg of pulp at a consistency of about 3 to 25%, in combination with about 0.01% to about 5% of one or more chemical mediators added to the pulp slurry, at a pH of about 4.5 to about 10, a temperature of between 25 and 75° C., for 20 to 120 minutes, as described in U.S. Pat. No. 6,241,849; and between 10 and 10,000 peroxidase units or 0.001 to 1000 of laccase units per gram of dry matter at a pH of between 4 and 10 and a temperature of between 20 and 90° C., at a consistency of between 0.5 and 25%, as described in U.S. Pat. No. 6,610,172; See also WO92/09741. These patents on the use of laccase for kraft bleaching, or treatment using the addition of transition metal ions in combination with laccase are not related to pitch control.

There exists a need for a method to reduce pitch deposition in the pulp and papermaking processes in an economic and effective manner.

Therefore, it is an object of this invention to provide a method for reducing and or modifying oleophilic and other wood extractives to reduce pitch deposition in pulp and papermaking processes.

BRIEF SUMMARY OF THE INVENTION

Methods of treating pulp stocks such as ground wood, semi-chemical, recycled and mechanical pulps, or Kraft pulp not having added transition metal compounds to facilitate enzymatic reactions, 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. The pulp stock, which may or may not have been treated with alum, is treated with an enzyme formulation containing oxidative enzymes, esterases, and/or combinations thereof. Oxidative enzymes include glucose oxidases, laccases, peroxidases and catalases, cholesterol oxidases, alcohol oxidases, L-ascorbate oxidase (EC 1.10.3.4) and polyvinyl-alcohol oxidase. 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. In one embodiment, the oxidative enzymes are formulated with a lipolytic enzyme, such as a lipase. Alternatively, the oxidative enzymes can be applied alone, either before or after treatment of the pulp stock with a lipolytic enzyme.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the effect of PD243 treatment on pitch deposition of Newsprint Mill A thermomechanical pulp (“TMP”) stock.

FIG. 2 is a graph showing the effect of PD243 treatment on pitch deposition of Newsprint Mill B TMP.

FIG. 3 is a graph slowing the effect of PD247 treatment on pitch deposition of Newsprint Mill A TMP stock.

FIG. 4 is a graph showing the comparison of enzyme formulations on pitch deposition of Newsprint Mill B TMP stock.

FIG. 5 is a graph showing, the effect of PD243 treatment time on pitch deposition of Newsprint B TMP stock.

DETAILED DESCRIPTION OF THE INVENTION

I. Definitions

“Pitch deposits” as used herein refers to a composition composed of low molecular weight olephilic materials (primarily triglycerides, resin acids, fatty acids, waxes, resin esters, fatty alcohols, sterols, and terpenes), as well as pectins, lignans, and phenolic compounds, which are released from wood fibers during chemical and mechanical pulping processes. Some of these resinous substances precipitate as aluminum, calcium and magnesium salts, causing problems with the wet end components of paper machines and affecting paper quality.

“Mechanical pulp” refers to pulp produced by reducing pulpwood logs and chips into fiber component by the use of mechanical energy, comprising stone ground wood pulp, pressurized ground wood pulp and thermomechanical pulp.

“Stone ground wood pulp” or “SGW” as used herein, refers to pulp which is produced by grinding wood into relatively short fibers with stone grinding. This pulp is used mainly in newsprint and wood-containing papers, such as lightweight coated (LWC) and super-calendered (SC) papers.

“Pressurized groundwood pulp” or “PGW” refers to pulp produced by a stone grinder where the whole grinder casing is pressurized and increased shower water temperature is used.

“Thermomechanical pulp” or “TMP” as used herein, refers to pulp that is produced in a thermo-mechanical process where wood chips or sawdust are softened by steam before entering a pressurized refiner. TMP generally has the same end-uses as stone groundwood pulp.

“Semi-chemical pulp” as used herein, refers to pulp produced by a combination of some chemicals (less than those used in Kraft pulping) and unpressurized mechanical processes. A variety of this pulp with pretreated chips at a temperature over 100° C. followed by refining at atmospheric pressure is called “semichemical mechanical pulp” or “SCMP”. This pulp has properties suitable for tissue manufacture.

“Chemo-Thermomechanical Pulp” or “CTMP” as used herein, refers to mechanical pulp produced by treating wood chips with chemicals (usually sodium sulfite) and steam before mechanical defiberization.

“Chemical pulp”, as used herein, refers to pulp produced by the treatment of wood chips or sawdust with chemicals to liberate the cellulose fibers by removing the binding agents such as lignin resins and gums. Sulphite and Sulphate or Kraft are two types of chemical pulping. Kraft is the predominant pulping process in chemical pulp production.

“Recycled pulp” or “recycled fibers” refers to fiber component of a paper or paperboard furnish that is derived from recycled paper and paperboard or wastepaper.

II. Material for the Enzymatic Treatment of Pulp Stocks

Methods of treating a pulp stock with an enzyme formulation including 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, are described herein. The enzyme formulations can be used to treat pulp stocks produced by mechanical pulping techniques such as thermomechanical pulping (“TMP”), groundwood pulping (“GWP”), and stone groundwood pulping (“SGW”); chemical pulping techniques such as chemo-thermomechanical pulping and Kraft pulping; and stocks produced from recycled fibers. The oxidative enzymes can be formulated with a lipolytic enzyme such as a lipase. Alternatively, the pulp stock can be treated with the oxidative enzymes before or after treatment with a lipolytic enzyme.

A. Enzymes

The enzyme formulations can include oxidative enzymes, esterases, and/or mixtures thereof. Oxidative enzymes include, but are not limited to, laccases, peroxidases, glucoses oxidases, cholesterol oxidases, alcohol oxidases, L-ascorbate oxidase (EC 1.10.3.4) and polyvinyl-alcohol oxidase.

i. Laccases

Laccases (EC 1.10.3.2) are classified as benzenediol:O₂ oxidoreductases and are further divided into subclasses based on the organism which produces the enzyme, the molecular weight of the enzyme, and the number of central copper atoms present in the enzyme. Laccases are polyphenol oxidases, which are produced by plants and white-rot fungi. Typical fungal laccases are metalloproteins which contain up to four copper atoms per molecule. Laccases catalyze the four electron reduction of molecular oxygen (O₂) to water with the concurrent oxidation of additional substrates. Laccases display broad substrate specificity and multifunctionality, including participation in lignin biosynthesis and degradation, methylation and demethylation of phenolic compounds, plant pathogenicity, bacterial melanization and the oxidation of unsaturated fatty acid esters (triglycerides) and their associated lipids.

Laccases can optionally be formulated with a laccase mediator, also known as a redox mediator. Suitable redox mediators include, but are not limited to, 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS); 6-hydroxy-2-naphthoic acid; 7-methoxy-2-naphtol; 7-amino-2-naphthalene sulfonic acid: 5-amino-2-naphthalene sulfonic acid; 1,5-diaminonaphthalene; 7-hydroxy-1,2-naph-thimidazole; 10-methylphenothiazine; 10-phenothiazinepropionic acid (PPT); N-hydroxysuccinimide-10-phenothiazinepropionate; benzidine; 3,3′-dimethylbenzidine; 3,3′-dimethoxybenzidine; 3,3′,5,5′-tetramethylbenzidine; 4′-hydroxy-4-biphenylcarboxylic acid; 4-amino-4′-methoxystilbene; 4,4′-diaminostilbene-2,2′-disulfonic acid; 4,4′-diaminodiphenylamine; 2,7-diaminofluorene; 4,4′-dihydroxy-biphenylene; triphenylamine; 10-ethyl-4-phenothiazinecarboxylic acid; 10-ethylphenothiazine; 10-propylphenothiazine; 10-isopropylphenothiazine; methyl-10-phenothiazinepropionate; 10-phenylphenothiazine; 10-allyl-phenothiazine; 10-phenoxazinepropionic acid (POP); 10-(3-(4-methyl-i-piperazinyl)propyl)phenothiazine; 10-(2-pyrrolidinoethyl)phenothiazine; 10-methylphenoxazine; iminostilbene; 2-(p-aminophenyl)-6-methylbenzothiazole-7-sulfonic acid; N-benzylidene-4-biphenylamine; 5-amino-2-naphthalenesulfonic acid; 7-methoxy-2-naphtol; 4,4′-dihydroxybenzophenone; N-(4-(dimethylamino)benzylidene)-p-anisidine; 3-methyl-2-benzothiazolinone(4-(dimethylamino)benzylidene)hydrazone; 2-acetyl-10-methylphenothiazine; 10-(2-hydroxyethyl)phenothiazine; 10-(2-hydroxyethyl)phenoxazine; 10-(3-hydroxypropyl)phenothiazine; 4,4′-dimethoxy-N-methyl-diphenylamine and vanillin azine.

ii Peroxidases

Peroxidases (EC 1.11.1) are enzymes that catalyze oxidation-reduction reactions (oxidoreductases). Peroxidases may include fatty acid-peroxidase, L-ascorbate peroxidase, peroxiredoxin, horseradish peroxidase. Fatty acid peroxidase acts on long-chain fatty acids from dodecanoic acid to octadecanoic acid. Peroxidases catalyze the decomposition of hydrogen peroxide which is a byproduct of the decomposition of superoxide and hydroxide radical produced by aerobic respiration in cells. Peroxidases reduce hydrogen peroxide to water while oxidizing a variety of substrates, including phenols, unsaturated fatty acids (triglycerides), resin acids and fatty acids.

The oxidation of resin acids, fatty acids, mono-, di-, and triglycerides, lignans, and phenols is a common chemical reaction that occurs in both plants and animals. The reaction is typically referred to as “lipid peroxidation” and results in the degradation of lipids. Unsaturated fatty acids, such as linoleic acid, may be oxidized in the presence of oxygen to generate radicals which can react further. Therefore, the physiochemical properties of pitch components may change, thus reducing pitch amount and pitch deposition.

iii. Esterases

Suitable esterases (EC 3.1.1.), include but are not limited to, carboxyl esterases such as acetyl esterases (EC 3.1.1.6), pectin esterases, lipases, and aceyl esterases (EC 3.1.1.6), which hydrolyze carboxylic esters. Examples of other suitable lipolytic enzymes include cholesterol esterase (EC 3.1.1.13), which hydrolyses sterol esters. Pectin esterases cleave the ester bonds liking pectin groups. Pectin is a family of compounds found in the cell walls of plants and trees and has been implicated in drainage and pitch deposition.

v. Lipolytic Enzymes

Mono-, di, and triglycerides in a wood pulp sample can be reduced, i.e. hydrolyzed, in the presence of a lipolytic enzyme, such as a lipase, to form glycerol and fatty acids. Preferably, the lipolytic enzyme is a non-selective lipase (EC 3.1.1.3) that can hydrolyze the ester bonds at all three locations in the glyceride stricture. Suitable lipases for the hydrolysis of triglycerides may be derived from plant, animal, or preferably microbial sources. Examples of sources for microbial lipases include Candida rugosa, Rhizopus arrhizus, and Chromobacterium viscosum. Other suitable lipolytic enzymes belong to the family of carboxylic ester hydrolases. Representative examples of these include phospholipases, lipoprotein lipase, and acylglycerol lipase.

In one embodiment, the enzyme formulation is PD243, which contains stabilizers, biocides, water, dispersants, and a laccase from Novozymes A/S. The application dosage of laccase may range from 1 to 10,000 laccase units (LAMU) per kilogram of oven dried fibers, preferably 10 to 5,000 LAMU per kilogram of oven dried fibers, more preferably 50 to 500 LAMU per kilogram of oven dried fibers.

Laccase units (LAMU) are based on the rate of oxidation of syringdazine. 1 LAMU is defined as the amount of enzyme which, under standard conditions, such as pH 7.5 and 30° C., oxidizes 1 mmol syringaldazine per minute. The laccase activity in LCU may also be determine using 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) as the substrate at 25° C. and pH4.5. One unit of enzyme activity is defined as the amount of enzyme oxidizing 1 mmol of ABTS per minute.

In another embodiment, the enzyme formulation is PD242 which contains stabilizers, biocides, water, dispersants, and a laccase from AB Enzymes GmbH. The laccase may be used in either powder form or liquid form by mixing with stabilizers, water and dispersants or dissolving it into either water or any buffer solutions with dispersants. The final application dosage of the laccase may range from 1 to 50,000 LCU per kilogram of oven dried fibers, preferably 10 to 110,000 LCU per kilogram of oven dried fibers, and more preferably 50 to 1000 LCU per kilogram of oven dried fibers.

In another embodiment, the enzyme formulation is PD247, which contains stabilizers, biocides, water and dispersants and peroxidase from Novozymes A/S. The final application dosage of the peroxidase may range from 2 to 20,000 peroxidase units (PU) per kilogram of oven dried fibers, preferably 20 to 10,000 PU per kilogram of oven dried fibers, and more preferably 100 to 5,000 PU per kilogram of oven dried fibers.

The activity of peroxidases is measured in peroxidase units (PU). One peroxidase unit is the amount of enzyme that catalyses the conversion of 1 μmol of H₂O₂ per minute in a system where 2,2″-azinobis(3-ethylbenzothiazoline-6-sulfonate), ABTS, is oxidized at pH 7.0 and temperature of 60° C.

The glucose oxidase catalyzes the oxidation of glucose to gluconic acid. The gluconic acid may be measured either by titration using a standard alkali or colormetric method using p-hydroxybenzoic. One glucose oxidase unit (GOU) is the amount of enzyme converts one micromole of glucose per minute at 35° C. at Ph 5.0.

EnzOx® PCX is one of the commercially formulated pitch control products available from Enzymatic Deinking Technologies (EDT), LLC, Norcross, Ga. EnzOx® PCX contains stabilizers, dispersants, biocides, cellulases, hemicellulases, amylases, pectinases and lipolytic enzymes which may hydrolyze triglycerides into glycerol and fatty acids, and loosen or liberate other pitch related extractives from stock fibers. The pitch extractives may therefore be oxidized by oxidizing enzymes such as laccases and peroxidases and then removed from the paper making process by additional dispersants.

It is believed that the oxidative enzymes react with resin acids, fatty acids, and esters thereof in the presence of oxygen, to generate reactive oxygen species which include hydroxyl radicals, lipid oxyl or peroxyl radicals, singlet oxygen, and superoxides. These reactive oxygen species can further react to form non-radical intermediates derived from unsaturated fatty acids, such as lipid hydroperoxides, thereby modifying the physiochemical properties of the pitch components and reducing pitch deposition.

B. Dispersants

The formulation may include one or more dispersants, which can be surfactants and/or polymers. Suitable surfactant dispersants include, but are not limited to, primary and branched alkoxylates, fatty acid alkoxylates phosphate esters and their alkoxylates, alkylphenol alkoxylates, block copolymers of ethylene and propylene oxide, alkanesulfonates, olefinsulfonates, fatty amine alkoxylates, glyceride alkoxylates, glycerol ester alkoxylates, sorbitan ester alkoxylates, polyethylene glycol esters, polyalkylene glycols, polyacrylic acids, sodium polyacrylate, acrylic acid copolymer, acrylate copolymer, acrylic crosslinked copolymer, and their derivatives; maleic acid and acrylic acid or acrylate copolymer, maleic acid/olefin copolymer, and their derivatives; polyvinyl alcohol/polyvinyl acetate copolymers, polyvinyl pyrrolidone, and their derivatives, and combinations thereof. The concentration of the surface active agent(s) is from about 1% to about 90% by weight of the formulation, more preferably from about 5% to about 20% by weight of the formulation. Their application dosage is from 0.005 lbs/ton to 20 lbs/ton of solid based on the oven-dried weight of stock fibers, preferably 0.0225 to 1.0 lbs/ton. They may be added alone or together with oxidative enzymes at the same addition locations or separately it different locations.

III. Methods of Treatment

The enzyme-based treatment can be applied at any one of various points during the pulping and paper manufacturing processes. Suitable locations include, but are not limited to, the latency chest, reject refiner chest, disk filter or decker feed or accept, TMP whitewater systems the low density (“LD”) chest, which is a storage chest for pulp; the medium density or consistency chest (MC), which is another storage chest for pulp, the high density (“HD”) chest, which is another storage chest for pulps the decker, which thickens the pulp; the blend chest; the machine chest; the headbox, which is the location just before the paper machine where the stock is prepared for the paper making process; the paper machine (“PM”) itself where the paper is actually made; and the white water system.

The enzyme-based treatments can be used to reduce pitch deposition in mechanical pulps such as thermomechanical pulps and groundwood pulps; chemical pulps such as chemo-thermomechanical pulps and kraft pulps, and pulps produced from recycled paper. Mechanical pulps may be treated with a lipolytic enzyme, such as a lipase, prior to treatment with the oxidative enzyme formulations in order to convert the triglycerides present in the pulp to glycerol and fatty acids. The oxidative enzymes can also react with neutral sterols, which are found in kraft pulps, as well as the adhesives and stickies which are carried over from the deinking of recovered paper.

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 pH of the stock can be adjusted using alum or aluminates. The stock can be treated for a period of time ranging from about 5 minutes to about 10 hours. The consistency of the pulp stock to be treated is between about 0.1% and 35%, more preferably between 0.5% and 10% In one embodiment, the oxidative enzymes are formulated with a lipolytic enzyme, such as a lipase. Alternatively, the oxidative enzymes can be applied before or after treatment of the pulp stock with a lipolytic enzyme.

EXAMPLES

A Stand Mixer with coated flat beaters, such as the Commercial 5 series from KitchenAid®, was used to determine the effect of enzyme formulations on the amount of pitch deposits on the beaters. The stainless steel mixing bowls were used to hold fiber stocks at consistency of about 3% to about 20%, preferably from about 8% to 10% and the mixing temperature was controlled with a water jacket at a temperature from about 25° C. to 95° C., preferably from about 50° C. to about 70° C. The pulp stocks were mixed at a mixing speed between “1” to “4”, preferably “2”. The stocks were mixed for a period of time ranging from about 5 minutes to about 10 hours, preferably from about 20 minutes to about 3 hours.

Representative stock from either the Blowline or the Decker was taken from Newsprint Mill A and Newsprint Mill B and used for the experiments. The pH of the stocks at these locations normally ranges from about 4.5 to about 6.5 and alum and aluminates were used for pH adjustment. The reaction pH was from about 4.0 to about 8.0, preferably from about 4.5 to about 5.5.

The procedures for pitch deposition tests to evaluate different enzyme formulations using kitchen mixer are as follows: 100 g oven dried fibers were weighed out and added to the mixing bowl. Water, heated to a temperature of 65° C. was added to the blow to prepare a stock with a final consistency of 8%. The stock was mixed for 10 minutes and the pH of the stock was adjusted, as needed. The enzyme formulation was added to the mixing bowl and mixed for 1 hour. The pulp stock was allowed to cool room temperature and then mixed for an additional 30 minutes. The amount of pitch deposit on the beaters from the control with no enzyme formulation treatment was treated as 100%, and the others were rated visually in percentage based on the deposition amount on their beaters. Alternatively, the beaters could be weighed to determine the difference in the pitch deposition.

Example 1

The Effect of PD243 Treatment on Pitch Deposition of Newsprint Mill A Thermomechanical Pulp Stock

The experiment was conducted following the procedure described above. The Decker accept stock from Newsprint Mill A was treated initially with EnzOx® PCX at a concentration of 0.1% based on the oven dried weight of the fibers and then with different amounts of the PD243 formulation. The results are shown in FIG. 1. FIG. 1 shows that the relative pitch deposition decreases as the dosage per ton of the enzyme formulation increases compared to the control which was not treated with the enzyme formulation.

Example 2

The Effect of PD243 Treatment on Pitch Deposition of Newsprint Mill B Thermomechanical Pulp Stock

The experiment was conducted following the procedure described above. The blowline stock from Newsprint Mill B was initially treated with EnzOx® PCX at a concentration of 0.1% based on the oven dried weight of the fibers and then with different amounts of the PD243 formulation. The results are shown in FIG. 2. FIG. 2 shows that the relative pitch deposition decreases as the dosage per ton of the enzyme increases compared to the control which was not treated with the enzyme formulation.

Example 3

The Effect of PD247 Treatment on Pitch Deposition of Newsprint Mill A Thermomechanical Pulp Stock

The experiment was conducted following the procedure described above. The blowline stock from Newsprint Mill A was initially treated with EnzOx® PCX at a concentration of 0.1% based on the oven dried weight of the fibers and then with different amounts of the PD247 formulation. The results are shown in FIG. 3. FIG. 3 shows that the relative pitch deposition decreases as the dosage per ton of the enzyme formulation increases compared to the control which was not treated with the enzyme formulation.

Example 4

The Effect of Different Enzyme Formulations on Pitch Deposition of Newsprint Mill B Thermomechanical Pulp Stock

The experiment was conducted following the procedure described above. The blowline stock from Newsprint Mill B was first treated with EnzOx® PCX at 0.1 based on oven-dry weight of fibers and then with 0.5 lbs per ton of PD242, PD243, and PD247. The results are shown in FIG. 4. FIG. 4 shows that the relative deposit amount for the treated sample was reduced significantly compared to the control which was not treated with any enzyme formulation.

Example 5

The Effect of PD243 Treatment Times on Pitch Deposition of Newsprint Mill B Thermomechanical Pulp Stock

The experiment was conducted following the procedure described above. The Decker accept stock from Newsprint Mill B was first treated with EnzOx® PCX at 0.1% based on oven dry weight of fibers and then with PD243 formulation at 0.15 lbs per ton for 0.5 and 3 hours. The results are shown in FIG. 5. FIG. 5 shows that the relative deposit amount for a 3 hour treatment was much less than for 0.5 hour treatment, and that the treatments showed little deposit compared to the control which was not treated with any enzyme formulation.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. The teachings of the references cited herein are specifically incorporated by reference.

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.

Claims

1. A method of reducing pitch deposition or controlling pitch related problems during the pulp and paper making process, the method comprising

treating a semi-chemical, recycled, or mechanical pulp stock or Kraft pulp not having added transition metal compounds to facilitate enzymatic reactions,

with an effective amount of a formulation of one or more oxidative enzymes selected from the group consisting of a formulation reducing pitch deposition, a formulation controlling pitch related problems, a formulation modifying 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, and a formulation changing the concentration of triglycerides, fatty acids, resin acids, and esters of fatty acids and resin acids.

2. The method of claim 1, wherein the one or more oxidative enzymes is selected from the group consisting of oxidases, peroxidases, and combinations thereof.

3. The method of claim 1 wherein the formulation further comprises one or more compounds selected from the group consisting of redox mediators, dispersants, surfactants and combinations thereof.

4. The method of claim 3 wherein the redox mediator is selected from the group consisting of 2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS); 6-hydroxy-2-naphtoic acid; 7-methoxy-2-naphtol; 7-amino-2-napththalene sulfonic acid; 5-amino-2-naphthalene sulfonic acid; 1,5-diaminonaphthalene; 7-hydroxy-1,2-naph-thimidazole; 10-methylphenothiazine; 10-phenothiazine-propionic acid (PPT); N-hydroxysuccinimide-10-phenothiazine-propionate; benzidine; 3,3′-dimethylbenzidine; 3,3′-dimethoxybenzidine; 3,3′,5,5′-tetramethylbenzidine; 4′-hydroxy-4-biphenylcarboxylic acid; 4-amino-4′-methoxystilbene; 4,4′-diaminostilbene-2,2′-disulfonic acid; 4,4′-diaminodiphenylamine; 2,7-diaminofluorene; 4,4′-dihydroxy-biphenylene; triphenylamine; 10-ethyl-4-phenothiazinecarboxylic acid; 10-ethylphenothiazine; 10-propyl-phenothiazine; 10-isopropyl phenothiazine; methyl-10-phenothiazinepropionate; 10-phenylphenothiazine; 10 allyl-phenothiazine; 10-phenoxazinepropionic acid (POP); 10-(3-(4-methyl-i-piperazinyl)propyl)phenothiazine; 10-(2-pyrrolidinoethyl)phenothiazine; 10-methylphenoxazine; iminostilbene; 2-p-aminophenyl)-6-methylbenzothiazole-7-sulfonic acid; N-benzylidene-4-biphenylamine; 5-amino-2-naphthalenesulfonic acid; 7-methoxy-2-naphtol; 4,4′-dihydroxybenzophenone; N-(4-(dimethylamino)benzylidene)-p-anisidine; 3-methyl-2-benzo-thiazolinone(4-(dimethylamino)benzylidene)hydrazone; 2-acetyl-10-methylphenothiazine; 10-(2-hydroxyethyl)phenothiazine; 10-hydroxyethyl)phenoxazine; 10-(3-hydroxypropyl)phenothiazine; 4,4′-dimethoxy-N-methyl-diphenylamine, and vanillin azine.

5. The method of claim 3 wherein the dispersant is selected from the group consisting of primary and branched alkoxylates, fatty acid alkoxylates, phosphate esters and their alkoxylates, alkylphenol alkoxylates, block copolymers of ethylene and propylene oxide, alkanesulfonates, olefinsulfonates, fatty amine alkoxylates, glyceride alkoxylates, glycerol ester alkoxylates, sorbitan ester alkoxylates, polyethylene glycol esters, polyalkylene glycols, polyacrylic acids, sodium polyacrylate, acrylic acid copolymer, acrylate copolymer, acrylic crosslinked copolymer, and their derivatives; maleic acid and acrylic acid or acrylate copolymer, maleic acid/olefin copolymer, and their derivatives, polyvinyl alcohol/polyvinyl acetate copolymers, polyvinyl pyrrolidone, and their derivatives, and combinations thereof.

6. The method of claim 2 wherein the oxidase enzymes are selected from the group consisting of laccases, glucose oxidases, alcohol oxidases, cholesterol oxidases, fatty acid oxidases, polyvinyl alcohol oxidases, and polyphenyl oxidases.

7. The method of claim 2 where the peroxidase enzymes are selected from the group consisting of fatty acid peroxidases, catalases and manganese peroxidases.

8. The method of claim 6 wherein the concentration of laccase is from about 1 to about 50,000 laccase units (LAMU or LCU) per kilogram of oven-dried fibers.

9. The method of claim 8, wherein the concentration of laccase is from about 10 to about 10,000 laccase units (LAMA or LCU) per kilogram of over-dried fibers.

10. The method of claim 8 wherein the concentration of laccase is from about 50 to about 1,000 laccase units (LAMU or LCU) per kilogram of oven-dried fibers.

11. The method of claim 7 wherein the concentration of peroxidase is from about 2 to about 20,000 peroxidase units (PU) per kilogram of oven dried fibers.

12. The method of claim 11 wherein the concentration of peroxidase is preferably from about 20 to about 10,000 peroxidase units (PU) per kilogram of oven-dried fibers.

13. The method of claim 11 wherein the concentration of peroxidase is from about 50 to about 5,000 peroxidase units (PU) per kilogram of OD oven dried fibers.

14. The method of claim 6 wherein the concentration of glucose oxidase is from about 1 to about 10,000 glucose oxidase units (GOU) per kilogram of oven dried fibers.

15. The method of claim 14 wherein the concentration of glucose oxidase is from about 10 to about 2,000 glucose oxidase unit (GOU) per kilogram of oven-dried fibers.

16. The method of claim 14 wherein the concentration of glucose oxidase is from about 50 to about 500 glucose oxidase units (GOU) per kilogram of OD oven dried fibers.

17. The method of claim 4 wherein the concentration of the redox mediator is from about 0.005 to about 3 kilograms/ton of oven dried fibers.

18. The method of claim 17 wherein the concentration of the redox mediator is from about 0.0002 to about 3 kilograms/ton of oven dried fibers.

19. The method of claim 5 wherein the concentration of the dispersant is from about 0.002 to about 10 kilograms/ton oven dried fibers.

20. The method of claim 19 wherein the concentration of the dispersant is from about 0.004 to about 3 kilograms/ton of oven dried fibers.

21. The method of claim 5 where the polyvinyl pyrrolidone and their derivatives is selected from the group consisting of a molecular weight between 7,000 to 2,500,000 daltons, more preferably between 400,000 and 2,000,000.

22. The method of claim 5 wherein the polyvinyl alcohol/polyvinyl acetate copolymers is selected from the group consisting of a molecular weight between 5,000 and 500,000 daltons, more preferably between 50,000 and 150,000, and a hydrolysis decree between 50% and 100%, more preferably between 70% and 95%.

23. The method of claim 1 wherein the pulp stock is produced by a process selected from the group consisting of mechanical pulping, semichemical pulping, chemi-theromomechanical pulping, bleached Kraft pulping and recovered fiber pulping.

24. The method of claim 1 wherein the pulp is a mechanical pulp selected from the group consisting of groundwood pulp, pressurized groundwood pulp and thermomechanical pulp.

25. The method of claim 1 wherein the pulp stock has been previously treated with a lipolytic enzyme.

26. The method of claim 1 further comprising treating the pulp stock with the oxidative enzyme in combination with a lipolytic enzyme.

27. The method of claim 1 wherein the pulp stock is subsequently treated with a lipolytic enzyme.

28. The method of claim 1 wherein the pulp stock is treated in a location selected from the group consisting, of the latency chest, the reject refiner chest, the disk filter and decker, TMP whitewater, the low density (“LD”) chest, the medium density (“MD”) chest, the high density (“HD”) chest, the decker, the blend chest, the machine chest, the headbox, the white water system, and the paper machine (“PM”).

29. The method of claim 1 wherein the formulation is maintained in the pulp stock at a temperature of about 30° C. to about 95° C.

30. The method of claim 29 wherein the formulation is maintained in the pulp stock at a temperature of about 50° C. to about 80° C.

31. The method of claim 1 wherein the formulation is maintained in the pulp stock at a pH of about 4.0 to about 7.0.

32. The method of claim 31 wherein the formulation is maintained in the pulp stock at a pH of about 4.5 to about 5.5.

33. The method of claim 1 wherein the pulp stock is treated with alum and an effective amount of one or more oxidative enzymes.

34. The method of claim 1 wherein the pulp stock is treated with laccase and an effective amount of one or more other oxidative enzymes.