METHOD OF MAKING PAPER OR BOARD

REFERENCE TO SEQUENCE LISTING

This application contains a Sequence Listing in computer readable form. The computer readable form is incorporated herein by reference.

SEQ ID No: 1 is a Q120H variant of the mature endoglucanase shown as SEQ ID NO: 9 of WO 96/29397.

SEQ ID No: 2 is a variant of endoglucanase.

FIELD OF THE INVENTION

The present invention relates to methods of making paper or board and methods of improving refinability and/or strengthening potential of pulp for use in a paper or board mill.

BACKGROUND OF THE INVENTION

Processes for the preparation of paper, such as printing, writing, decorative, special or tissue-type papers, and/or board, such as kraft liner, test liner, corrugating medium or boxboard, through the use of cellulose pulps are known.

To impart desired papermaking properties in cellulosic fiber, pulp is subjected to mechanical processing—termed refining. Within the refiner, pulp is exposed to tension, compression and shear during transit between rotating systems of grooved metal plates and stators. Although effective, refining consumes a significant fraction of the total energy required during the manufacture of paper and board.

Enzymes are known in the art as means to alter the response of cellulosic fiber to refining to reduce manufacturing costs and/or improve certain properties of paper and board. Natural or modified polymers are generally added after or in the absence of refining to improve pulp performance (e.g. drainage, dewatering, retention, etc.) within the paper machine—reduce manufacturing costs—and provide desired structural and strength properties in the finished goods.

WO14058557 describes a method of producing paper or paperboard, wherein an enzyme and a polymer is added during the process. WO17029238 relates to an aqueous surface treatment composition for paper and board comprising degraded starch. In WO17034774, a method of making paper and paper products is described where a composition comprising laccase, lipase and cationic fixative polymer is used as an additive to a lignocellulosic suspension.

However, there is a finite degree to which the known processes reduce manufacturing costs and/or impart value within the finished paper and board. There is thus a need for an improved process for preparation of paper or board.

SUMMARY OF THE INVENTION

In one aspect the invention provides mixtures comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent that is useful for making paper or board and for improving refinability and/or strengthening potential of pulp for use in a paper or board mill.

In a further aspect the invention provides a method of making paper or board comprising the steps of:

- a) introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a once-dried or never-dried pulp slurry prior to refining, to form a treated pulp slurry,
- b) refining the treated pulp slurry to form a refined, treated pulp slurry, and
- c) forming the refined, treated pulp slurry into paper or board.

In another aspect, the method of improving refinability and/or strengthening potential of pulp for use in a paper or board mill comprises a step of introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a once-dried or never-dried pulp slurry prior to or after refining in the paper or board mill.

In a further aspect, the treated pulp slurry is refined to a target property selected from the group consisting of: reduced freeness of a refined, treated pulp slurry, increased tensile strength of a paper or board product, an increased structural property of a paper or board product, and combinations thereof.

In a further aspect, the invention provides a method of making a pulp or pulp slurry, comprising:

- a) introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to refining, and
- b) refining the treated pulp or pulp slurry to form a refined, treated pulp or pulp slurry.

In a further aspect, the invention provides a method of making a pulp or pulp slurry, comprising: introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to or after refining to obtain a refined, treated pulp or pulp slurry.

In one aspect the mixture disclosed in this specification comprises at least one carbohydrate-active enzyme and at least one liquid natural polymer, and optionally at least one strength agent.

In another aspect a modified liquid natural polymer disclosed in this specification is made by the process of mixing a natural polymer with at least one carbohydrate-active enzyme and optionally at least one strength agent. In yet another aspect the refined, treated pulp slurries are made by the process of introducing to a once-dried or never-dried pulp slurry a mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent, prior to refining the pulp slurry, and reacting the mixture with the pulp slurry for sufficient time to improve at least one property of the pulp slurry for use in making paper or board products. In still another aspect the refined, treated pulp slurries are made by the process of introducing to a once-dried or never-dried pulp slurry a mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent prior to refining the pulp slurry, and reacting the mixture with the pulp slurry for sufficient time that the pulp slurries have a freeness of between 10 ml and 890 ml.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 presents the effect of pre-treatments of different dosage levels of LNP and of two different carbohydrate active enzymes on the tensile strength of handsheets prepared from the treated fiber. ‘EGA’ and ‘EGB’ denote cellulases of SEQ ID 1 and SEQ ID 2, respectively. The extension ‘50’ and ‘100’ denote dosing levels of 50 grams per ton of dry fiber and 100 grams per ton of dry fiber, respectively.

FIG. 2 presents the effect of pre-treatments of different dosage levels of LNP and of two different carbohydrate active enzymes on the burst strength index of handsheets prepared from the treated fiber. ‘EGA’ and ‘EGB’ denote cellulases of SEQ ID 1 and SEQ ID 2, respectively. The extension ‘50’ and ‘100’ denote dosing levels of 50 grams per ton of dry fiber and 100 grams per ton of dry fiber, respectively.

FIG. 3 presents the effect of the various pre-treatments on the tensile strength indices of handsheets prepared from fiber subjected to various degrees of PFI beating.

FIG. 4 presents a comparison between the freeness of beaten pulps prepared from pre-treated fiber and the tensile strength indices of handsheets prepared from the pre-treated and beaten fiber.

FIG. 5 presents the effect of pre-treatments on the bulk of handsheets prepared from fiber subjected to various degrees of PFI beating.

FIG. 6 presents a comparison between tensile strength indices and bulk in handsheets prepared from fiber subjected to the various pretreatments and to various degrees of PFI beating.

FIG. 7 presents the effect of pre-treatments on tensile index of handsheets prepared from treated-BEKP.

FIG. 8 presents the effect of pre-treatments on burst index of handsheets prepared from treated-BEKP.

FIG. 9 presents the effect of pre-treatments on tensile index of handsheets prepared from treated-BEKP and refined-BSKP at a ratio of 1:1 (w/w).

DEFINITIONS

As used herein, the singular forms “a”, “an”, and “the” include plural references unless indicated otherwise, expressly or by context. For example, “a” natural polymer includes one or more natural polymers, unless indicated otherwise, expressly or by context.

Within this specification all recited ranges include all subranges within the recited range.

Within the specification and claims TAPPI refers to the Technical Association of the Pulp and Paper Industry, which promulgates standards and guidelines for test methods. Such methods are routinely used within the pulp and paper industry and are available at http://www.TAPPI.org/Publications-Standards/Standards-Methods.

Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulosic fibers from wood, fiber crops or waste paper. Consequently, pulp is herein understood as a fluid mixture of fiber and water used to make paper.

Pulp slurry refers to a suspension of fiber within a liquid phase. The slurry can be formed using various suitable liquids (e.g. water) and with various ratios of either component and therefore can be described by a range of weight or volume-based consistency values (e.g. solids content, moisture content, etc.).

With specific reference to the method the pulp slurry is the suspension of fiber within a liquid phase before refining and addition of the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to the pulp slurry. Addition of the at least one carbohydrate-active enzyme, the at least one liquid natural polymer, and optionally the at least one strength agent forms a treated pulp slurry, and refining of the treated pulp slurry forms a refined, treated pulp slurry.

Standard handsheets are handsheets prepared according to TAPPI Standard T 205: “Forming handsheets for physical tests of pulp”.

Refining is the mechanical treatment of pulp fibers to impart to them the appropriate characteristics for papermaking.

Without being bound by theory, or definition, it is believed that refining fibrillates the surface of the fiber and delaminates the fiber wall to influence the flexibility and conformability of the whole fiber. It is further theorized that increased flexibility, external fibrillation and surface area improves the inter-fiber bonding potential associated with certain optical, structural and mechanical properties, with neighbouring fibers during the production of paper and board.

Refining may be performed by any appropriate process, illustrative processes include, but are not limited to, processes in which pulp slurries are refined between rotating and occasionally static metal elements of, for example, laboratory beaters, or industrial disk or conical refiners.

Freeness is a measure of how quickly water is able to drain from a sample of dilute fiber. A sample's freeness decreases as the drainage rate decreases.

In some embodiments there is a correlation between freeness values and a target level of refining of pulp. In some other embodiments, there is a correlation between freeness values and the ease of drainage of water from the wet web. In still other embodiments, where there is a correlation between freeness and ease of drainage of water from the wet web, the freeness and ease of drainage are mostly highly correlated in the early sections of the forming section of the paper machine.

Freeness can be measured by any standard method. An illustrative test for measuring freeness is based on gravity dewatering through a screen. In such methods, the devices are designed so that an operator can judge the rate of dewatering by observing the volume of liquid collected in a graduated cylinder.

Fines are objects small enough to pass through a conical hole having a maximum diameter of 76 micrometers. As related to the disclosed methods and claims, fines include, but are not limited to, small cellulosic materials, parenchyma cells, and other small cells from wood.

A natural polymer is a polymer occurring in nature and may e.g. have its origin in plants or animals. Examples of suitable natural polymers include but are not limited to starch, cellulose, proteins and natural rubber.

Liquid natural polymers (LNP) are natural polymers modified through at least one means of chemical (e.g. etherification, acetylation, propylation, phosphating, ethylation, acidulation, oxidation, enzymatic), physical and/or mechanical conversion to obtain the natural polymer in liquid form.

Strength agents are natural or synthetic additives employed to improve fiber bonding.

Lignocellulosic fibers are fibers from plant dry matter, such as wood, and comprise carbohydrate polymers, such as e.g. cellulose and hemicellulose, and an aromatic polymer such as e.g. lignin.

A wet end system is generally the part of the stock preparation and paper or board machine that contacts a slurry of fibers, fillers, and/or other additives.

In embodiments, the wet end system includes all of the unit operations between the brown stock washers to the press section where water is pressed from the wet fibrous web and any combination of subunits therein.

A dry end system is the part of the papermaking system after the wet-press section (i.e. dryer section to roll).

Runnability describes the efficiency with which a furnish—comprising a slurry of papermaking fiber and various additives—undergoes consolidation into a fibrous web via water removal across elements of the paper or board machine. Several pulp properties can influence the runnability of the furnish on the machine for example, including, but not limited to freeness.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are methods of making paper or board, and compositions or mixtures useful for improving paper products. Also disclosed herein are methods of improving at least one property of a pulp slurry for use in a paper or board mill. In one aspect the improved property relates to improving the refinability of the pulp slurry and/or strengthening potential of the pulp slurry and/or the runnability of the pulp slurry and/or at least one structural property of paper and board, including but not limited to tensile strength and/or the bulk of the paper or board.

It has surprisingly been found by the inventors, that a combination of at least one liquid natural polymer and at least one carbohydrate-active enzyme when applied to a pulp slurry prior to refining during a process of making paper or paper board results in a refined, treated pulp slurry with improved properties including handsheet strengthening, tensile strength at unchanged or higher bulk, greater freeness, decrease in energy required during refining to meet a tensile strength target of a paper or board product compared to refined pulp slurries that have not been treated with said combination of liquid natural polymer(s) and carbohydrate-active enzyme(s).

As illustrated in FIGS. 3, 7, 8, and 9, the combined pre-treatment with liquid natural polymer and cellulase surprisingly provided an advantage in terms of handsheet strengthening relative to the control and either component added alone.

Surprisingly, the combined application of liquid natural polymer and cellulase prior to refining also provided the greatest tensile strength while delivering greater freeness than the control or either component when added alone (see FIG. 4).

Cellulases are known to improve the tensile strength of paper or board products, such as e.g. standard handsheets, often at the expense of bulk. When applied in concert with cellulase, liquid natural polymer surprisingly mitigated the loss of bulk (see FIG. 5). Furthermore, pretreatment with the blend of liquid natural polymer and cellulase provided higher tensile strength at higher bulk in resultant handsheets prepared from the refined fiber (see FIG. 6).

The carbohydrate-active enzyme modifies lignocellulosic fibers in the pulp slurry. In turn, the mixture of the at least one carbohydrate-active enzyme, at least one liquid natural polymer improves the properties of the pulp slurry beyond the use of the enzyme or liquid natural polymer alone. Thus, in one aspect, the properties of the pulp slurry are improved after at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added to a pulp slurry prior to refining. In another aspect, the properties of the pulp slurry are improved after at least one carbohydrate-active enzyme and at least one liquid natural polymer are added to a pulp slurry prior to refining, and optionally at least one strength agent is added to the pulp slurry after refining. In a further aspect, the strengthening potential of pulp slurry is improved after at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added to a pulp slurry prior to refining. In another aspect, the strengthening potential of pulp slurry is improved after at least one carbohydrate-active enzyme and at least one liquid natural polymer are added to a pulp slurry prior to refining, and optionally at least one strength agent is added to the pulp slurry after refining. In yet a further aspect, the structural properties, for example bulk of the paper or board product, prepared from the refined, treated, pulp slurry treated with at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent prior to refining are improved. In another aspect, the structural properties, for example bulk of the paper or board product, prepared from the refined, treated, pulp slurry treated with at least one carbohydrate-active enzyme and at least one liquid natural polymer are added to a pulp slurry prior to refining, and optionally at least one strength agent is added to the pulp slurry after refining.

In a still further aspect, the at least one carbohydrate-active enzyme is a cellulase, and the at least one liquid natural polymer is derived from starch. Such treatment may also be referred to as a pre-treatment.

Enzymes suitable for use in the method described herein are carbohydrate-active enzymes, i.e. enzymes which modify, disrupt or create glycosidic bonds. In one aspect, the carbohydrate active enzyme is from the CAZy database, i.e. a database of Carbohydrate-Active enzymes (also called CAZymes) known to the person skilled in the art and e.g. described by Lombard, V. et al. in “The carbohydrate-active enzymes database (CAZy) in 2013”. Nucleic Acids Research, 42 (D1): D490-D495. In one aspect, the at least one carbohydrate-active enzyme is a cellulase. In a further aspect, the at least one carbohydrate-active enzyme is an endoglucanase. In a still further aspect the at least one carbohydrate-active enzyme is a GH45. In an even further aspect, the at least one carbohydrate-active enzyme has an amino acid sequence which is at least 80%, 85%, 90%, 95% or 99% identical to SEQ ID No: 1. In a yet further aspect, the at least one carbohydrate-active enzyme has the amino acid sequence of SEQ ID No: 1 or has an amino acid sequence with up to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes compared to SEQ ID No: 1. In an even further aspect, the at least one carbohydrate-active enzyme has an amino acid sequence which is at least 80%, 85%, 90%, 95% or 99% identical to SEQ ID No: 2. In a still further aspect, the at least one carbohydrate-active enzyme has the amino acid sequence of SEQ ID No: 2 or has an amino acid sequence with up to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes compared to SEQ ID No: 2.

Liquid natural polymers suitable for use in the methods described herein include natural polymers. Such polymers are natural polymers that have been modified through at least one chemical (e.g. etherification, acetylation, propylation, phosphating, ethylation, acidulation, oxidation, enzymatic), physical and/or mechanical conversion means to obtain the natural polymer in liquid form. In an aspect, the liquid natural polymer is derived from one or more vegetal sources. In still another aspect the vegetal material is starch. In yet another aspect, the starch may be derived from corn, waxy maize, cassava, waxy cassava, wheat, potato, rice and pea (or other pulse source, including but not limited to fava bean or lentil), as well as other high amylose or low amylose variants of the vegetal source where a low amylose sources comprises no more than 10% amylose, or less than 5% amylose, or less than 3% amylose, or essentially no amylose (about 0%), and where high amylose sources comprise at least 40% amylose, or at least 50% amylose or at least 60% amylose, or at least 70% amylose, or between about 40% and 80% amylose. In still yet another aspect the liquid natural polymer is derived from a waxy starch. In even still another aspect the liquid natural polymer is derived from a waxy corn starch.

Strength agents may also be added to the liquid natural polymers. In one aspect the combination of at least one liquid natural polymer and at least one carbohydrate-active enzyme for use in the present invention further comprises at least one strength agent. In another aspect, the strength agents suitable for use with the disclosed methods and claims include, but are not limited to, natural or synthetic additives employed to improve fiber bonding. In yet another aspect such additives include, but are not limited to, carboxymethyl cellulose (CMC), glyoxalated polyacrylamide (GPAM), polyamide-epichlorohydrin (PAE), polyaminoamide-epichlorohydrin (PAAE), cationic polyacrylamide (CPAM), anionic polyacrylamide (APAM), amphoteric polyacrylamide, urea-formaldehyde (UF) and melamineformaldehyde (MF).

In an aspect the at least one carbohydrate-active enzyme is added to the natural polymer during, before or after it has been converted to a liquid natural polymer. In another aspect the at least one carbohydrate-active enzyme is added to the natural polymer after it has been converted to a liquid natural polymer. Natural polymers, for example starch, can be converted to liquid natural polymers using any suitable process, including but not limited to means of chemical (e.g. etherification, acetylation, propylation, phosphating, ethylation, acidulation, oxidation, enzymatic), physical and/or mechanical conversion to obtain the natural polymer in liquid form. The manner in which the at least one carbohydrate-active enzyme is added to the polymer depends on the liquefaction process as the enzyme is added at an appropriate time to ensure the enzyme remains functional within the enzyme/liquid natural polymer mixture. Considerations include for example, but are not limited to, whether the at least one carbohydrate-active polymer will withstand the pH, temperature, pressure, sheer, or any combination thereof used during the liquefaction process. In one aspect the at least one carbohydrate-active enzyme is added to the liquid natural polymer after it is converted from a natural polymer.

As disclosed herein, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added to a pulp slurry prior to refining the treated pulp slurry. In another aspect, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added to a pulp slurry in the pulper of a non-integrated paper mill, or a stock tower or equivalent storage vessel, in an integrated paper mill.

In one aspect of the method the pulp slurry is pre-incubated before addition of the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent for between 1 minute and 1 hour, or between 10 minutes and 40 minutes or between 15 minutes and 30 minutes. In an additional aspect of the method, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent may be applied to a pulp slurry and allowed to react with the pulp slurry for sufficient time to improve at least one property of the pulp slurry for making paper or board, or between 1 minute and 6 hours, or between 10 minutes and 5 hours, or between 20 minutes and 4 hours or between 30 minutes and 3 hours, or between 40 minutes and 2 hours or between 40 minutes and 1 hour, wherein the pulp slurry optionally has been preheated to 50-70° C. such as to about 60° C. prior to the addition of the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent. In a further aspect the reaction between the mixture of the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent and the pulp slurry is stopped by inactivating the enzyme by for example, adjusting the temperature of the treated pulp slurry or adjusting the pH of the treated pulp slurry. In a still further aspect the enzyme in the treated slurry is inactivated by adding sodium hypochlorite. In a yet further aspect of the method, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are applied to a pulp slurry at the same time or sequentially within between 1 second to 6 hours to allow interaction between the carbohydrate-active enzyme(s), liquid natural polymer(s) and pulp prior to refining the treated pulp slurry. In another aspect, the at least one enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added sequentially within one hour of each other, such as within between 1 second and five minutes of each other. In still another aspect, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are combined as a mixture, and then added together in a common composition to the pulp slurry. In yet another aspect, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent may be mixed in an addition pipeline or other feedline that feeds the resulting mixture to an introduction port, such as a port on a pulp processing unit or prior to the suction side of a pump between units. In a further aspect the at least one carbohydrate-active enzyme, the at least one liquid natural polymer, and optionally at least one strength agent are combined into a single suspension before being added to the pulp slurry. In even another aspect, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are added simultaneously to the pulp from different, separated introduction ports on the same processing unit. In still another aspect the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent are introduced sequentially as one or more addition streams from the same or different introduction ports or locations on the papermaking system within a short period of time. In aspects using sequential stream addition, the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent components are separately added in time with both components brought into contact with the pulp within the pulp slurry within a short period of time, for example, within about 5 minutes of each other, or within about 4 minutes of each other, or within about 3 minutes of each other, or within about 2 minutes of each other, or within about 1 minute of each other, or within about 30 seconds of each other, or within shorter periods of time.

In another aspect, after contacting the pulp with the at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent, the resulting treated pulp slurry may be further processed, for example by refining, and employed in the formation of paper or board.

In one aspect the mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength ingredient is added to the pulp slurry at a temperature between about 30 degrees and about 80 degrees centigrade, or between about 40 degrees and about 70 degrees centigrade or between about 50 degrees and about 60 degrees centigrade. In another aspect the mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength ingredient is added to the pulp slurry at pH between about 4.0 and about 10, or between about 5.0 and about 9.0 or between about 6.0 and about 8.0. In yet another aspect the at least one liquid natural polymer is added to the pulp slurry or to the mixture comprising the at least one carbohydrate-active enzyme and the optional at least one strength additive in an amount between 0.01% and 5.0% by weight of the pulp being treated, or between 0.05% and 2.0% by weight of the pulp being treated or between 0.10% and 2.0% by weight of the pulp being treated or between 0.10% and 1.0% by weight of the pulp being treated, or about 0.5% by weight of the pulp being treated. In even another aspect, the at least one carbohydrate-active enzyme is added to the pulp slurry or to the mixture of the at least one liquid natural polymer and the optional strength agent in an amount between 25 g and 200 g per metric ton of dry fiber or between 0.005% and 0.1% of dry fiber. By definition the pulp slurries may have various concentrations, but in embodiments the pulp slurry comprises between 1% and 20% fiber, or between 5% and 15% fiber, or about 10% fiber. Additionally, by definition pulp slurries may use various suspension liquids, such liquids may vary over pH as described above. In embodiments the suspension fluid is deionized water, which has a pH between pH 6.0 and 8.0. In embodiments, the suspension fluid is mill process water such as e.g. fresh water or water recycled from within the mill and/or recovered from water treatment operations, and pH is between pH 6.0 and 8.0.

In one aspect of the method the treated pulp slurry is refined to reduce its freeness. In another aspect the freeness, as measured by a freeness tester (for example as available from TAPPI Test Method T 227 om-99, “Freeness of pulp (Canadian standard method)”), is between 20 ml and 890 ml, and all subranges within.

In one aspect of the method, the refined, treated pulp slurry increases the tensile strength of the paper or board product. In another aspect the tensile strength of the product, as measured by tensile testing machine (for example as available from TAPPI T 494, “Tensile Breaking Properties of Paper and Paperboard (Using Constant Rate of Elongation Apparatus)”) is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g, or between 40 and 70 Nm/g, or between about 45 Nm/g and 65 Nm/g, and all subranges within. In still another aspect, the tensile strength of the paper or board product varies with the amount of refining of the treated pulp slurry. In yet another aspect the tensile strength is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g, or between 40 and 70 Nm/g, or between about 45 Nm/g and 65 Nm/g over a range of 0 to 1600 revolutions of a PFI mill. As illustrated in FIGS. 3, 7, 8, and 9, the combined pre-treatment with at the least one liquid natural polymer and the at least one carbohydrate-active enzyme surprisingly provided an advantage in terms of handsheet strengthening relative to the control and either component added alone. In another aspect, surprisingly the combined application of the at least one liquid natural polymer and the at least one carbohydrate-active enzyme added to the pulp slurry prior to refining also provided greater tensile strength while delivering greater freeness than the control or either component when added alone, as shown in FIG. 4. In yet still another aspect, the tensile strength index is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g or between 40 and 70 Nm/g or between about 45 Nm/g and 65 Nm/g over a freeness range of between 390 ml and 490 ml.

In one aspect of the method the refined, treated pulp slurry increases or preserves the bulk of the paper or board product relative to paper or board products prepared after carbohydrate enzyme treatment alone. In a further aspect, the paper or board product is a standard handsheet. In another aspect the bulk is calculated by dividing the thickness of a sheet by its basis weight is between 0.1 cm³/g and 2.0 cm³/g, and all subranges within. In still another aspect, this result is unexpected as cellulases are known to improve the tensile strength of paper or board products, such as e.g. standard handsheets, at the expense of bulk. But, when applied in concert the cellulose and liquid natural polymer surprisingly mitigated the loss of bulk, as shown in FIG. 5. In embodiments the bulk of paper or board products, such as e.g. standard handsheets, using the treated pulp slurry is within 7.5% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within 7% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within 6.5% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within 6% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within 5.5% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within 5% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining, or within between about 7.5% and 0.1% of the same paper or board products, such as e.g. standard handsheets, using untreated pulp slurry at the same level of refining. In yet another aspect, pretreatment with the blend of liquid natural polymer and cellulase provided higher tensile strength and higher bulk in resultant handsheets prepared from the refined, treated pulp slurry, as shown in FIG. 6. In embodiments, the paper or board product will have a bulk of between 0.25 cm³/g and 0.35 cm³/g or between 0.28 cm³/g and 0.34 cm³/g, or between 0.29 cm³/g and 0.33 cm³/g while having a tensile strength of between 45 Nm/g and 65 Nm/g.

In one aspect of the method, with reference to FIGS. 2 and 8 paper or board products made using the treated and refined pulp slurry have a higher burst strength index at the same level of refining. In another aspect the burst strength index of handsheets made from refined, treated pulp is between about 3 and about 3.5 kPa m²/g.

The method described herein may be practiced within conventional papermaking operations with modifications that may be easily made in view of the present disclosure. The method may be practiced, for example, in wet end operations before the refiner as part of conventional papermaking operations with modifications that may be easily made in view of the present disclosure. The method may employ many different types of papermaking pulp or combinations thereof. The method may be practiced to make of any grade for example, including, but not limited to printing and writing paper, medium grade paper, paperboard, linerboard, tissue paper, towel paper and moulded packaging.

This specification further discloses a method of making a pulp or pulp slurry, comprising:

- a) introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to refining, and
- b) refining the treated pulp or pulp slurry to form a refined, treated pulp or pulp slurry.

This specification further discloses a method of making a pulp or pulp slurry, comprising: introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to or after refining to obtain a refined, treated pulp or pulp slurry.

This specification further discloses a mixture comprising a carbohydrate-active enzyme, at least one liquid natural polymer, and optionally a strength agent. In one aspect the mixture is made by the process of mixing at least one carbohydrate-active enzyme, at least one liquid natural polymer and optionally at least one strengthening agent. In another aspect the mixture is made by the further process of contacting the at least one carbohydrate-active enzyme and at least one liquid natural polymer.

In one aspect the carbohydrate active enzyme from the CAZy database, i.e. a database of Carbohydrate-Active enzymes (also called CAZymes) known to the person skilled in the art and e.g. described by Lombard, V. et al. in “The carbohydrate-active enzymes database (CAZy) in 2013”. Nucleic Acids Research, 42 (D1): D490-D495. In another aspect, the at least one carbohydrate-active enzyme is a cellulase. In a further aspect, the at least one carbohydrate-active enzyme is an endoglucanase. In a still further aspect, the at least one carbohydrate-active enzyme is a GH45. In an even further aspect, the at least one carbohydrate-active enzyme has an amino acid sequence which is at least 80%, 85%, 90%, 95% or 99% identical to SEQ ID No: 1. In a yet further aspect, the at least one carbohydrate-active enzyme has the amino acid sequence of SEQ ID No: 1 or has an amino acid sequence with up to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes compared to SEQ ID No: 1. In an even yet further aspect, the at least one carbohydrate-active enzyme has an amino acid sequence which is at least 80%, 85%, 90%, 95% or 99% identical to SEQ ID No: 2. In a yet still further aspect, the at least one carbohydrate-active enzyme has the amino acid sequence of SEQ ID No: 2 or has an amino acid sequence with up to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes compared to SEQ ID No: 2.

Liquid natural polymers suitable for use in the mixture include natural polymers. Such polymers are natural polymers that have been modified through at least one of chemical (e.g. etherification, acetylation, propylation, phosphating, ethylation, acidulation, oxidation, enzymatic), physical and/or mechanical conversion means to obtain the natural polymer in liquid form. In an aspect, the liquid natural polymer is derived from one or more vegetal sources. In still another aspect the vegetal material is starch. In yet another aspect, the starch may be derived from corn, waxy maize, cassava, waxy cassava, wheat, potato, rice and pea (or other pulse source, including but not limited to fava bean or lentil), as well as other high amylose or low amylose variants of the vegetal source where a low amylose sources comprises no more than 10% amylose, or less than 5% amylose, or less than 3% amylose, or essentially no amylose (about 0%), and where high amylose sources comprise at least 40% amylose, or at least 50% amylose or at least 60% amylose, or at least 70% amylose, or between about 40% and 80% amylose. In still yet another embodiment aspect the liquid natural polymer is derived from a waxy starch. In even still another embodiment the liquid natural polymer is derived from a waxy corn starch.

In one aspect the strength agents that optionally may be used in the mixture include but are not limited to natural or synthetic additives employed to improve fiber bonding. In another aspect such agents include, but are not limited to, carboxymethyl cellulose (CMC), glyoxalated polyacrylamide (GPAM), polyamide-epichlorohydrin (PAE), polyaminoamide-epichlorohydrin (PAAE), cationic polyacrylamide (CPAM), anionic polyacrylamide (APAM), amphoteric polyacrylamide, urea-formaldehyde (UF) and melamineformaldehyde (MF).

In one aspect the specification discloses a treated pulp slurry, and a refined, treated pulp slurry. In another aspect the specification discloses a treated pulp slurry made by the process of introducing into a pulp slurry prior to refining a mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a once-dried or never-dried pulp slurry prior to refining, and reacting the mixture with the pulp slurry for sufficient time to improve at least one property of the pulp slurry for use in making paper. In a further aspect the refined, treated pulp slurry made according to the foregoing process has a freeness of between 20 ml and 890 ml, and all subranges within.

In one aspect the mixture comprised of at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent is used to make a refined, treated pulp slurry that increases the tensile strength of the paper or board product. In another aspect the tensile strength index of the product, as measured by a tensile testing machine, is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g, or between 40 and 70 Nm/g, or between about 45 Nm/g and 65 Nm/g, and all subranges within. In still another aspect, the tensile strength index of the paper or board product varies with the amount of refining of the treated pulp slurry. In yet another aspect the tensile strength is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g, or between 40 and 70 Nm/g, or between about 45 Nm/g and 65 Nm/g over a range of 0 to 1600 revolutions of a PFI mill. As illustrated in FIGS. 3, 7, 8, and 9, the pre-treatment of the pulp slurry with the mixture comprising the at least one carbohydrate-active enzyme and the least one liquid natural polymer surprisingly provided an advantage in terms of handsheet strengthening relative to the control and either component added alone. In another aspect, surprisingly the combined application of the at least one liquid natural polymer and the at least one carbohydrate-active enzyme added to the pulp slurry prior to refining also provided greater tensile strength while delivering greater freeness than the control or either component when added alone, as shown in FIG. 4. In yet still another aspect, the tensile strength index is between 10 Nm/g and 100 Nm/g, or between 20 Nm/g and 80 Nm/g or between 40 and 70 Nm/g or between about 45 Nm/g and 65 Nm/g over a freeness range of between 390 ml and 490 ml.

In one aspect the mixture comprising at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent is used to increase or preserve the bulk of the paper or board products relative to paper or board products prepared after carbohydrate enzyme treatment alone. In a further aspect, the paper or board product is a standard handsheet. In another aspect the bulk is calculated by dividing the thickness of a sheet by its basis weight. In embodiments the bulk of the paper or board product is between 0.1 cm³/g and 2.0 cm³/g and all subranges within. In still another aspect, this result is unexpected as cellulases are known to improve the tensile strength of paper or board products at the expense of bulk. But, when applied in concert the cellulose and liquid natural polymer surprisingly mitigate the loss of bulk, as shown in FIG. 5. In embodiments the bulk of paper or board products, such as e.g. standard handsheets using the treated pulp slurry is within 7.5% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining, or within 7% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining, or within 6.5% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining, or within 6% of the same using untreated pulp slurry at the same level of refining, or within 5.5% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining, or within 5% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining, or within between about 7.5% and 0.1% of the same paper or board products, such as e.g. standard handsheets using untreated pulp slurry at the same level of refining. In yet another aspect, pretreatment with the blend of liquid natural polymer and cellulase provided higher tensile strength at higher bulk in resultant handsheets prepared from the refined fiber, as shown in FIG. 6. In embodiments, the paper or board products, such as e.g. standard handsheets will have a bulk of between 0.25 cm³/g and 0.35 cm³/g or between 0.28 cm³/g and 0.34 cm³/g, or between 0.29 cm³/g and 0.33 cm³/g while having a tensile strength of between 45 Nm/g and 65 Nm/g.

Pulps and pulp slurries used in accordance with aspects of the disclosure may comprise virgin and/or recovered fibers. Any nonwood, softwood or hardwood fiber typically used in the paper industry may be employed, including, but not limited to bleached and unbleached chemical pulp. Non-limiting examples of fibers include but are not limited to: Bleached eucalyptus kraft (BEK) fiber, Bleached acacia kraft (BAK) fiber, Bleached hardwood kraft (BHK) fiber, Unbleached hardwood kraft (UBHK) fiber, Northern bleached softwood (NBSK) fiber Southern bleached softwood kraft (SBSK) fiber Unbleached softwood kraft (UBSK) fiber, Old corrugated container (OCC), Mixed office waste (MOW), Deinked pulp (DIP), and bleached and non-bleached non-wood fiber.

In an aspect the treated pulp slurry may be used to make a paper or a board. In another aspect the paper or board made from the treated pulp slurry may be used to make paper or a board of any grade. In still another aspect the paper made from the treated pulp slurry may be used to make of the grades selected from the group consisting of printing and writing paper, medium, paperboard, linerboard, tissue, towel and moulded packaging.

Preferred Aspects

Preferred aspects of the invention are given below.

1. A method of making paper or board comprising:

- a) introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a once-dried or never-dried pulp slurry prior to refining,
- b) refining the treated pulp slurry to form a refined, treated pulp slurry, and
- c) forming the refined, treated pulp slurry into paper or board.
  
  2. The method according to aspect 1, wherein the treated pulp slurry is refined to a target property selected from the group consisting of: reduced freeness of the refined, treated pulp slurry, increased tensile strength of the paper or board product, increased structural property of the paper or board product, decreased energy required during refining to meet a tensile strength target of a paper or board product, and a combination thereof.
  
  3. The method according to aspect 1 or 2, wherein the treated pulp slurry is refined to a reduced freeness.
  
  4. The method according to any one of aspects 1-3, wherein the freeness is measured according to the standard Canadian procedure (TAPPI test method T 227 om-99) and is between 30 ml and 890 ml.
  
  5. The method according to any one of aspects 1-4, wherein the treated pulp slurry is refined to an increased tensile strength.
  
  6. The method according to any one of aspects 1-5, wherein the tensile strength is a tensile strength index, which is measured according to TAPPI test method T 220 sp-16, and is between 10 Nm/g and 100 Nm/g.
  
  7. The method according to any one of aspects 1-6, wherein the treated pulp slurry is refined to an increased structural property of the paper or board product.
  
  8. The method according to any one of aspects 1-7, wherein the structural property is the bulk of the paper or board, which is measured according to TAPPI test method T 220 sp-16, and is between 0.1 cm³/g and 2.0 cm³/g.
  
  9. The method according to any one of aspects 1-8, wherein the treated pulp slurry is refined to a target property, which is a decreased energy required during refining to meet a tensile strength target of a paper or board product.
  
  10. The method according to any one of aspects 1-9, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are introduced as two separate addition streams.
  
  11. The method according to any one of aspects 1-9, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are combined into one suspension before being introduced to the pulp slurry.
  
  12. The method according to any one of aspects 1-11, wherein the liquid natural polymer is derived from at least one vegetal source.
  
  13. The method according to any one of aspects 1-12, wherein the vegetal source is starch from a source selected from the group consisting of corn, waxy maize, cassava, waxy cassava, wheat, potato, rice and/or pulse, and high or low amylose variants thereof.
  
  14. The method according to any one of aspects 1-13, wherein at least one strength agent is introduced to a once-dried or never-dried pulp slurry prior to refining.
  
  15. The method according to any one of aspects 1-14, wherein the at least one strength agent is selected from the group consisting of: carboxymethyl cellulose (CMC), Glyoxalated Polyacrylamide (GPAM), Polyamide-Epichlorohydrin (PAE), Polyaminoamide-Epichlorohydrin (PAAE), Cationic Polyacrylamide (CPAM), Anionic Polyacrylamide (APAM), Amphoteric Polyacrylamide, Urea-Formaldehyde (UF) and Melamineformaldehyde (MF).
  
  16. The method according to any one of aspects 1-15, wherein the liquid natural polymer is derived from a waxy starch.
  
  17. The method according to any one of aspects 1-16, wherein the liquid natural polymer is derived from a waxy corn starch.
  
  18. The method according to any one of aspects 1-17, wherein the carbohydrate-active enzyme is still active when the liquid natural polymer is added.
  
  19. The method according to any one of aspects 1-18, wherein the carbohydrate-active enzyme consists of one component only.
  
  20. The method according to any one of aspects 1-19, wherein the carbohydrate-active enzyme is a cellulase.
  
  21. The method according to any one of aspects 1-20, wherein the cellulase is an endoglucanase.
  
  22. The method according to aspect 21, wherein the endoglucanase is a GH45.
  
  23. The method according to any one of aspects 21-22, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2.
  
  24. The method according to any one of aspects 21-23, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into the sequence.
  
  25. The method according to aspect 24, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  26. The method according to any one of aspects 21-25, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2.
  
  27. The method according to aspect 23, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 1.
  
  28. The method according to aspect 24, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into SEQ ID No: 1.
  
  29. The method according to aspect 28, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  30. The method according to aspect 26, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1.
  
  31. The method according to aspect 26, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 2.
  
  32. The method according to aspect 23, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 2.
  
  33. The method according to aspect 24, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 2, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into SEQ ID No: 2.
  
  34. The method according to aspect 33, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  35. The method according to any one of aspects 1-34, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry in the pulper of a non-integrated paper mill, or a stock tower or storage vessel, in an integrated paper mill.
  
  36. The method according to any one of aspects 1-35, wherein the pulp slurry is treated with the at least one carbohydrate-active enzyme and the at least one liquid natural polymer for a period of time up to 6 hours.
  
  37. The method according to any one of aspects 1-36, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry at a temperature of from about 30 degrees centigrade to about 80 degrees centigrade, at a temperature of from about 40 degrees centigrade to 70 degrees centigrade, or at a temperature of from about 50 degrees centigrade to 60 degrees centigrade.
  
  38. The method according to any one of aspects 1-37, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry at a pH from about 4.0 to about 10, at a pH from about 5.0 to about 9.0, or at a pH from about 6.0 to about 8.0.
  
  39. The method according to any one of aspects 1-38, wherein the liquid natural polymer is in a dose from 0.01% to 5.0%—such as about 0.5%—of the weight of the total dry solids in the pulp being treated.
  
  40. The method according to any one of aspects 1-39, wherein the liquid natural polymer is in a dose from 0.05% to 2.0% of the weight of the total dry solids in the pulp being treated.
  
  41. The method according to any one of aspects 1-40, wherein the liquid natural polymer is in a dose from 0.10% to 2.0% of the weight of the total dry solids in the pulp being treated.
  
  42. The method according to any one of aspects 1-41, wherein the liquid natural polymer is in a dose from 0.10% to 1.0% of the weight of the total dry solids in the pulp being treated.
  
  43. The method according to any one of aspects 1-42, wherein the at least one carbohydrate-active enzyme is in an amount from 25 g to 200 g of formulated enzyme product per dry metric ton of fiber.
  
  44. The method according to any one of aspects 1-43, wherein the at least one carbohydrate-active enzyme is in an amount from 0.005% to 0.1% of dry fiber.
  
  45. The method according to any one of aspects 1-44, wherein the fiber is a papermaking fiber.
  
  46. The method according to any one of aspects 1-45, wherein the fiber is selected from the group consisting of Bleached eucalyptus kraft (BEK) fiber, Bleached acacia kraft (BAK) fiber, Bleached hardwood kraft (BHK) fiber Unbleached hardwood kraft (UHK) fiber, Northern bleached softwood kraft (NBSK) fiber, Southern bleached softwood kraft (SBSK) fiber Unbleached softwood kraft (UBSK) fiber, Old corrugated container (OCC), Mixed office waste (MOW), Deinked pulp (DIP), and bleached and non-bleached non-wood fiber.
  
  47. The method according to any one of aspects 1-46, wherein the fiber is bleached eucalyptus kraft fiber.
  
  48. The method according to any one of aspects 1-47, wherein the pulp, paper or board is selected from the group consisting of: printing paper, writing paper, corrugating medium, paperboard, linerboard (kraft and test), tissue, towel, boxboard and moulded packaging.
  
  49. The method according to any one of aspects 1-48, wherein the method is used in paper mills or pulp mills.
  
  50. The method according to any one of aspects 1-49, wherein the method is used in a pulp mill in a unit operation in the final brownstock washer, the pulp dryer, the wet stock tower or storage vessel of the paper, the board mill or between these unit operations.
  
  51. The method according to any one of aspects 1-49, wherein the method is used in a paper mill in the wet end systems.
  
  52. The method according to aspect 51, wherein the method is used for producing paper grades selected from the group consisting of: printing & writing paper, medium, paperboard, linerboard, boxboard, tissue, towel and moulded packaging.
  
  53. The method according to any one of aspects 1-52, wherein the paper or board product is a standard handsheet.
  
  54. A method of improving at least one property of a pulp slurry for use in a paper or board mill, wherein at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent is introduced to a once-dried or never-dried pulp slurry prior to refining in the paper or board mill thereby making a treated pulp slurry having at least one improved property.
  
  55. The method of aspect 54, wherein the improved property is one or more properties selected from the group consisting of: reducing freeness of the refined, treated pulp slurry, increasing the tensile strength of the paper or board product made from the treated pulp slurry, increasing the structural property of the paper or board product made from the treated pulp slurry, decreasing the energy required during refining to meet a tensile strength target of a paper or board product, and a combination thereof.
  
  56. The method of aspect 54 or 55, wherein the treated pulp slurry is further refined to further reduce the freeness of the treated pulps slurry.
  
  57. The method according to any one of aspects 54-56, wherein the treated pulp slurry is refined to a reduced freeness.
  
  58. The method according to any one of aspects 54-57, wherein the freeness is measured according to the standard Canadian procedure (TAPPI test method T 227 om-99) and is between 30 ml and 890 ml.
  
  59. The method according to any one of aspects 54-58, wherein the treated pulp slurry is refined to an increased tensile strength.
  
  60. The method according to any one of aspects 54-59, wherein the tensile strength is a tensile strength index, which is measured according to TAPPI test method T 220 sp-16 and is between 10 Nm/g and 100 Nm/g.
  
  61. The method according to any one of aspects 54-60, wherein the treated pulp slurry is refined to an increased structural property of the paper or board product.
  
  62. The method according to any one of aspects 54-61, wherein the structural property is the bulk property which is calculated according to TAPPI test method T 220 sp-16 and is between 0.1 cm³/g and 2.0 cm³/g.
  
  63. The method according to any one of aspects 54-62, wherein the treated pulp slurry is refined to a target property, which is a decreased energy required during refining to meet a tensile strength target of a paper or board product.
  
  64. The method according to any one of aspects 54-63, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are introduced as two separate addition streams.
  
  65. The method according to any one of aspects 54-63, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are combined into one suspension before introduced to the pulp slurry.
  
  66. The method according to any one of aspects 54-65, wherein the liquid natural polymer is derived from at least one vegetal source.
  
  67. The method according to any one of aspects 54-66, wherein the vegetal source is starch from a source selected from the group consisting of corn, waxy maize, cassava, waxy cassava, wheat, potato, rice and/or pea, and high or low amylose variants thereof.
  
  68. The method according to any one of aspects 54-67, wherein at least one strength agent is introduced to a once-dried or never-dried pulp slurry prior to refining.
  
  69. The method according to any one of aspects 54-68, wherein the at least one strength agent is selected from the group consisting of: carboxymethyl cellulose (CMC), Glyoxalated Polyacrylamide (GPAM), Polyamide-Epichlorohydrin (PAE), Polyaminoamide-Epichlorohydrin (PAAE), Cationic Polyacrylamide (CPAM), Anionic Polyacrylamide (APAM), Amphoteric Polyacrylamide, Urea-Formaldehyde (UF) and Melamineformaldehyde (MF).
  
  70. The method according to any one of aspects 54-69, wherein the liquid natural polymer is derived from a waxy starch.
  
  71. The method according to any one of aspects 54-70, wherein the liquid natural polymer is derived from a waxy corn starch.
  
  72. The method according to any one of aspects 54-71, wherein the carbohydrate-active enzyme is still active when the liquid natural polymer is added.
  
  73. The method according to any one of aspects 54-72, wherein the carbohydrate-active enzyme consists of one component only.
  
  74. The method according to any one of aspects 54-73, wherein the carbohydrate-active enzyme is a cellulase.
  
  75. The method according to aspect 74, wherein the cellulase is an endoglucanase.
  
  76. The method according to aspect 75, wherein the endoglucanase is a GH45.
  
  77. The method according to any one of aspects 74-75, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2.
  
  78. The method according to any one of aspects 74-76, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into the sequence.
  
  79. The method according to aspect 78, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  80. The method according to any one of aspects 74-77, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1 or SEQ ID No: 2.
  
  81. The method according to any one of aspects 74-79, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 1.
  
  82. The method according to any one of aspects 74-79 or 81, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into SEQ ID No: 1.
  
  83. The method according to aspect 82, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  84. The method according to any one of aspects 74-77 or 80, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 1.
  
  85. The method according to any one of aspects 74-79, wherein the endoglucanase has an amino acid sequence which is at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% identical to the amino acid sequence of SEQ ID No: 2.
  
  86. The method according to any one of aspects 74-79 or 85, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 2, wherein up to 10, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, amino acid changes, such as substitutions, have been introduced into SEQ ID No: 2.
  
  87. The method according to aspect 86, wherein the amino acid changes are conservative amino acid substitutions or insertions that do not significantly affect the folding and/or activity of the endoglucanase.
  
  88. The method according to any one of aspects 74-77 or 80, wherein the endoglucanase has the amino acid sequence of SEQ ID No: 2.
  
  89. The method according to any one of aspects 54-88, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry in the pulper of a non-integrated paper mill, or a stock tower or storage vessel, in an integrated paper mill.
  
  90. The method according to any one of aspects 54-89, wherein the pulp slurry is treated with the at least one carbohydrate-active enzyme and the at least one liquid natural polymer for a period of time up to 6 hours.
  
  91. The method according to any one of aspects 54-90, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry at a temperature of from about 30 degrees centigrade to about 80 degrees centigrade, at a temperature of from about 40 degrees centigrade to 70 degrees centigrade, or at a temperature of from about 50 degrees centigrade to 60 degrees centigrade.
  
  92. The method according to any one of aspects 54-91, wherein the at least one carbohydrate-active enzyme and the at least one liquid natural polymer are added to a pulp slurry at a pH from about 4.0 to about 10, at a pH from about 5.0 to about 9.0, or at a pH from about 6.0 to about 8.0.
  
  93. The method according to any one of aspects 54-92, wherein the liquid natural polymer is in a dose from 0.01% to 5.0%—such as about 0.5%—of the weight of the total dry solids in the pulp being treated.
  
  94. The method according to any one of aspects 54-93, wherein the liquid natural polymer is in a dose from 0.05% to 2.0% of the weight of the total dry solids in the pulp being treated.
  
  95. The method according to any one of aspects 54-94, wherein the liquid natural polymer is in a dose from 0.10% to 2.0% of the weight of the total dry solids in the pulp being treated.
  
  96. The method according to any one of aspects 54-95, wherein the liquid natural polymer is in a dose from 0.10% to 1.0% of the weight of the total dry solids in the pulp being treated.
  
  97. The method according to any one of aspects 54-96, wherein the at least one carbohydrate-active enzyme is in an amount from 25 g to 200 g of formulated enzyme product per dry metric ton of fiber.
  
  98. The method according to any one of aspects 54-97, wherein the at least one carbohydrate-active enzyme is in an amount from 0.005% to 0.1% of dry fiber.
  
  99. The method according to any one of aspects 54-98, wherein the fiber is a papermaking fiber.
  
  100. The method according to any one of aspects 54-99, wherein the fiber is selected from the group consisting of Bleached eucalyptus kraft (BEK) fiber, Bleached acacia kraft (BAK) fiber, Bleached hardwood kraft (BHK) fiber Unbleached hardwood kraft (UHK) fiber, Northern bleached softwood kraft (NBSK) fiber, Southern bleached softwood kraft (SBSK) fiber Unbleached softwood kraft (UBSK) fiber, Old corrugated container (OCC), Mixed office waste (MOW), Deinked pulp (DIP), and bleached and non-bleached non-wood fiber.
  
  101. The method according to any one of aspects 54-100, wherein the fiber is bleached eucalyptus kraft fiber.
  
  102. The method according to any one of aspects 54-101, wherein the pulp, paper or board is selected from the group consisting of: printing paper, writing paper, corrugating medium, linerboard (kraft and test), tissue, towel, and boxboard.
  
  103. The method according to any one of aspects 54-102, wherein the method is used in paper mills or pulp mills.
  
  104. The method according to any one of aspects 54-103, wherein the method is used in a pulp mill in a unit operation in the final brownstock washer, the pulp dryer, the wet stock tower or storage vessel of the paper, the board mill or between these unit operations.
  
  105. The method according to any one of aspects 54-103, wherein the method is used in a paper mill in the wet end systems.
  
  106. The method according to aspect 105, wherein the method is used for producing paper grades selected from the group consisting of: printing & writing paper, medium, linerboard, tissue and towel.
  
  107. The method of making a pulp or pulp slurry, comprising:
- a) introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to refining, and
- b) refining the treated pulp or pulp slurry to form a refined, treated pulp or pulp slurry.
  
  108. A method of making paper or board or for making a pulp or pulp slurry, comprising: introducing at least one carbohydrate-active enzyme, at least one liquid natural polymer, and optionally at least one strength agent to a pulp or pulp slurry prior to or after refining to obtain a treated pulp or pulp slurry to form a refined, treated pulp or pulp slurry.
  
  109. The method of aspect 108 further comprising any one of aspects 1 to 107.
  
  110. A mixture comprising at least one carbohydrate-active enzyme and at least one liquid natural polymer, and optionally a strength agent.
  
  111. A mixture for use in making paper or board comprising at least one carbohydrate-active enzyme and at least one liquid natural polymer, and optionally a strength agent.

112. The mixture according to aspect 110 or 111 for use in making a pulp slurry having a freeness, measured according to the standard Canadian procedure (TAPPI test method T 227 om-99), of between 30 ml and 890 ml.

113. The mixture according to any one of aspects 110-112 for use in making a paper or board product having a tensile strength, as measured by TAPPI test method T 220 sp-16, of between 10 Nm/g and 100 Nm/g.

114. The mixture according to any one of aspects 110-113 for use in making a paper or board product having a bulk, calculated according to TAPPI test method T 220 sp-16, of between 0.1 cm³/g and 2.0 cm³/g.

115. A treated pulp or pulp slurry made by the method according to any one of aspects 1-109.

116. A treated pulp or pulp slurry having a freeness, measured according to the standard Canadian procedure (TAPPI test method T 227 om-99), of between 30 ml and 890 ml.

117. A paper or board product made using the treated pulp slurry according to aspect 115 or 116 having a tensile strength, as measured by TAPPI test method T 220 sp-16, of between 10 Nm/g and 100 Nm/g.

118. A paper or board product made using the treated pulp slurry according to any one of aspects 115-117 having a bulk, calculated according to TAPPI test method T 220 sp-16, of between 0.1 cm³/g and 2.0 cm³/g.

119. The paper or board product according to aspect 117 or 118, which is selected from the group consisting of: printing paper, writing paper, medium grade paper, paperboard, linerboard, tissue paper, towel paper and moulded packaging.

The invention is further described by the following examples which are not intended to be limiting in any way; a person of ordinary skill in the art would understand that variations can be made to the methods and products disclosed in the examples that would be within the spirit of the invention and the scope of the claims.

EXAMPLES
Example 1—Pretreatment of Cellulosic Fiber with a Combination of Liquid Natural Polymer and Enzyme

Ten pulp samples—equivalent to 24 grams of oven dry bleached eucalyptus kraft fiber each—were prepared by diluting never-dried pulp fiber to 10% w/w consistency with deionized water. The resultant pulp slurries (pH 7.8) were then pre-incubated for 20 minutes at 40° C. After pre-incubation, a liquid composition of liquid natural polymer, LNP derived from waxy corn starch, cellulase A of SEQ ID No: 1 from Novozymes (Bagsvaerd, Denmark) and/or cellulase B of SEQ ID No: 2 from Novozymes (Bagsvaerd, Denmark) were added to the 10 pre-heated aliquots according to table 1.

TABLE 1

LNP
Cellulase A
Cellulase B

Sample #
Identifier
(kg/t)
(g/t)
(g/t)

1
Control
—
—
—

2
EGA50
—
50
—

3
EGA100
—
100
—

4
EGB50
—
—
50

5
EGB100
—
—
100

6
LNP
5
—
—

7
LNP + EGA50
5
50
—

8
LNP + EGA100
5
100
—

9
LNP + EGB50
5
—
50

10
LNP + EGB100
5
—
100

When applicable, formulated liquid natural polymer was added to deliver 5 kg of dry waxy corn starch per metric ton of oven dry bleached eucalyptus kraft fiber. When applicable, formulated cellulases of SEQ ID No: 1 and SEQ ID No: 2 were added to deliver 50 or 100 g of formulated cellulase per metric ton of oven dry fiber. All pulps were incubated for 60 min at 40° C. and pH 7.8 within a kettle reactor immersed in a water bath. Continuous agitation was provided by an impeller.

After incubation, sodium hypochlorite was added to each pulp to deactivate the enzyme. Note: All pulps received same amount of hypochlorite (20 ppm active chlorine).

All pulps were diluted to 0.3% consistency for freeness determinations according to TAPPI standard T 227 om-99. Each pulp was used to prepare six 1.2 g (60 g/m²) handsheets according to TAPPI standard T 205. Physical testing (e.g. Tensile and burst strength indices) was performed according to the respective TAPPI standard procedures.

Results

As illustrated in FIG. 1 and FIG. 2, the combined pre-treatment with liquid natural polymer and either cellulase surprisingly provided an advantage in terms of handsheet strengthening relative to the control and either component added alone.

Example 2—Pre-Refiner Pretreatment of Cellulosic Fiber with a Combination of Liquid Natural Polymer and Enzyme

Thirteen pulp slurries were prepared by diluting 24 grams of oven dry equivalents of never-dried bleached eucalyptus kraft fiber to 10% w/w consistency with deionized water. The resultant pulp slurries (pH 7.8) were then pre-incubated separately for 20 minutes at 40° C. After pre-incubation, the pulp slurry was divided into one group of four and three groups of three. The first group of four served as the untreated control group (labelled “Control”). The first group of 3 slurries (labelled “LNP”), were treated with a liquefied waxy corn starch (Ingredion, Westchester, Ill.). The second group of 3 slurries were treated with cellulase A of SEQ ID No: 1 from Novozymes (Bagsvaerd, Denmark) (labelled “Cellulase A”). The third group of 3 slurries was treated with both the Cellulase A and the liquefied waxy corn starch (labelled “LNP+Cellulase A”). In all relevant instances, formulated liquefied waxy corn starch was added to deliver 5 kg of dry waxy corn starch per metric ton of oven dry bleached eucalyptus kraft fiber. In all relevant instances, formulated Cellulase A of SEQ ID No: 1 was added to deliver 100 g of formulated cellulase per metric ton of oven dry fiber. All pulps were incubated for 60 min at 40° C. and pH 7.8 within a kettle reactor immersed in a water bath. Continuous agitation was provided by an impeller.

After incubation, sodium hypochlorite was added to each pulp to deactivate the enzyme. Note that all pulps received same amount of hypochlorite (20 ppm active chlorine).

Pulp pads were prepared by vacuum filtration. The filtrate was passed once back across the pad to capture small materials (e.g. fragmented fibers and fines). Filtrates from each pulp were used to dilute the respective pads to 10% w/w consistency. Pulps from the control and each group of pre-treatments were subjected to 0, 500 & 1500 revolutions of beating within a standard PFI mill operating with 0.2 mm gap and a load of 1765 N/mm of bar length. Subsequently, the pulps were diluted to 0.3% consistency for freeness determinations according to TAPPI standard T 227 om-99. Each slurry was used to prepare six 1.2 g (60 g/m²) handsheets according to TAPPI standard T 205. Physical testing (e.g. Tensile and burst strength indices) was performed according to the respective TAPPI standard procedures.

Results

As illustrated in FIG. 3, the combined pre-treatment of fiber with liquid natural polymer and cellulase surprisingly provided an advantage in terms of handsheet strengthening relative to the control and either component added alone.

Cellulases are known to improve the tensile strength of paper or board products, such as e.g. standard handsheet at the expense of bulk. When applied in concert with cellulase, liquid natural polymer surprisingly mitigated the loss of bulk (see FIG. 5). Furthermore, pretreatment with the blend of liquid natural polymer and cellulase provided higher tensile at higher bulk in resultant handsheets prepared from the refined fiber (see FIG. 6).

Example 3—Pretreatment of Cellulosic Fiber with a Combination of Liquid Natural Polymer and Enzyme

Once-dried bleached eucalyptus kraft pulp (BEKP) was soaked in deionized water at 10% w/w consistency at room temperature overnight and was repulped at 500 rpm for 5 minutes. The resultant pulp was concentrated by centrifuge, dispersed, and stored at 4° C. before use.

Four pulp samples—equivalent to 24 grams of oven dry fiber each—were prepared by diluting to 4.0% w/w consistency with deionized water. The resultant pulp slurries (pH 6.8) were then pre-incubated for 30 minutes at 40° C. After pre-incubation, a liquid composition of liquid natural polymer, LNP derived from waxy corn starch, and cellulase A of SEQ ID No: 1 from Novozymes (Bagsvaerd, Denmark) were added to the pre-heated pulp slurries according to Table 2.

TABLE 2

LNP
Cellulase A

Sample #
Identifier
(kg/t)
(g/t)

1
BEKP-ctrl
—
—

2
BEKP-Enz
—
150

³

BEKP-LNP
7.5
—

4
BEKP-LNP/Enz
7.5
150

When applicable, the formulated liquid natural polymer was added to deliver 7.5 kg of starch solids per metric ton of oven dry fiber. When applicable, formulated cellulase of SEQ ID No: 1 was added to deliver 150 g of formulated cellulase per metric ton of oven dry fiber. All pulps were incubated for 30 min at 40° C. and pH 6.8 within a kettle reactor immersed in a water bath. Continuous agitation was provided by an impeller.

After incubation, sodium hypochlorite was added to each pulp slurry to deactivate the enzyme. Note: All pulps received same amount of hypochlorite (20 ppm active chlorine).

All pulps were diluted to 1.2% consistency for disintegration and further diluted to 0.3% consistency for freeness determinations according to TAPPI standard T 227 om-99. Each pulp was used to prepare six 1.2 g (60 g/m²) handsheets according to TAPPI standard T 205. Physical testing (e.g. tensile and burst strength indices) was performed according to the respective TAPPI standard procedures.

Results

As illustrated in FIGS. 7 and 8, the combined pre-treatment with liquid natural polymer and cellulase surprisingly provided an advantage in terms of handsheet strengthening relative to the control or either component added alone.

Example 4—Pretreatment of Cellulosic Fiber with a Combination of Liquid Natural Polymer and Enzyme

Once-dried bleached eucalyptus kraft pulp (BEKP) was soaked in deionized water at 10% w/w consistency at room temperature overnight and was repulped at 500 rpm for 5 minutes. The resultant pulp was thickened by centrifuge, dispersed, and stored at 4° C. before use.

Four BEKP samples—equivalent to 24 grams of oven dry fiber each—were prepared by diluting to 4.0% w/w consistency with deionized water. The resultant pulp slurries (pH 6.8) were then pre-incubated for 30 minutes at 40° C. After pre-incubation, a liquid composition of liquid natural polymer, LNP derived from waxy corn starch, and cellulase A of SEQ ID No: 1 from Novozymes (Bagsvaerd, Denmark) were added to the pre-heated pulp slurries according to Table 3.

When applicable, formulated liquid natural polymer was added to deliver 7.5 kg of starch solids per metric ton of oven dry fiber. When applicable, formulated cellulase of SEQ ID No: 1 was added to deliver 150 g of formulated cellulase per metric ton of oven dry fiber. All pulps were incubated for 30 min at 40° C. and pH 6.8 within a kettle reactor immersed in a water bath. Continuous agitation was provided by an impeller.

After incubation, sodium hypochlorite was added to each pulp to deactivate the enzyme. Note: All pulps received same amount of hypochlorite (20 ppm active chlorine).

All BEKP samples were diluted to 1.2% w/w consistency for disintegration, and further diluted to 0.3% w/w consistency for freeness determinations according to TAPPI standard T 227 om-99.

TABLE 3

LNP
Cellulase A

Sample #
Identifier
(kg/t)
(g/t)
PFI refining

1
BEKP-ctrl
—
—
—

2
BEKP-Enz
—
150
—

3
BEKP-LNP
7.5
—
—

4
BEKP-LNP/Enz
7.5
150
—

5
BSKP
—
—
1765 N/m of bar

length, 0.2 mm

gap, 1500 rev

Once-dried bleached softwood kraft pulp (BSKP) was soaked in deionized water at 10% w/w consistency at room temperature overnight and was repulped at 500 rpm for 7 minutes. The resultant pulp was thickened by centrifuge, dispersed, and stored at 4° C. before use.

One BSKP sample—equivalent to 24 grams of oven dry fiber—was prepared by diluting to 4.0% w/w consistency with deionized water. The resultant pulp slurry (pH 5.4) was adjusted to pH 6.8 by adding about 0.2 ml of 1M NaOH solution then incubated for 60 minutes at 40° C.

After incubation, the BSKP sample was concentrated to 10% w/w consistency and refined using a PFI refiner according to the conditions in Table 3.

After refining, the BSKP sample was diluted to 1.2% w/w consistency for disintegration and further diluted to 0.3% w/w consistency.

Each BEKP (0.3% w/w consistency) was blended with refined BSKP (0.3% w/w consistency) at the ratio of 1/1 (w/w) and used to prepare six 1.2 g (60 g/m²) handsheets according to TAPPI standard T 205. Physical testing (e.g. tensile and burst strength indices) was performed according to the respective TAPPI standard procedures.

Results

As demonstrated in FIG. 9, the combined pre-treatment with liquid natural polymer and cellulase significantly increased tensile strength relative to the control or either component added alone.

METHOD OF MAKING PAPER OR BOARD

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

PCT Information

Provisional Applications (1)