Method for pitch control in papermaking

Abstract

A method for pitch control in papermaking comprising adding to a furnish a pitch control additive comprising a talc-based pitch control additive and a non-talc pitch control additive component.

Description

METHOD FOR PITCH CONTROL IN PAPERMAKINGCROSS-REFERENCE TO RELATED APPLICATION

[0001] The benefit of priority to U.S. Provisional Patent Application No. 63 / 539,992 filed September 22, 2023, is hereby claimed and the disclosure is incorporated herein by reference in its entirety.FIELD

[0002] The disclosure relates to a method of controlling pitch in a papermaking process, and more particularly the use of a precipitated calcium carbonate-cellulose composite fiber and / or clusters of calcite particles for controlling pitch.BACKGROUND

[0003] Many papermakers use talc to scavenge non-productive deposits from the wet end of the papermaking machines to reduce agglomeration of such deposits on the papermaking machine, which can ultimately transfer to and lead to defects in the final paper. Pitch or ‘stickies’ control additives continually fix or absorb these impurities into small agglomerates that leave the wet end, so they do not show as defects in the final paper.SUMMARY

[0004] A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process in accordance with the disclosure can include adding a pitch control additive to a wood pulp furnish, the pitch control additive comprising a non-talc pitch control additive component comprising composite fibers, thereby reducing an amount of talcbased pitch control additive component needed for pitch control in the papermaking process. The composite fibers adsorb pitch from the wood pulp furnish and prevents agglomeration of pitch particles. Each composite fibers comprise a mineral attached to a fiber, wherein the mineral is at least 90 wt% based on the total weight of the composite fiber.

[0005] A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process in accordance with the disclosure can include adding a pitch control additive comprising a non-talc pitch control additive component comprising a precipitated calcium carbonate to a wood pulp furnish, thereby reducing an amount of talc-based pitch control additive component needed for pitch control in the papermaking process. The precipitated calcium carbonate comprises clusters of calcite particles with a specific surface area of about 1 .0 m2 / g to about 5.0 m2 / g. The pitch control additive component comprises atleast 20 wt% of the clusters of calcite particles based on the total weight of the pitch control additive.

[0006] A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process in accordance with the disclosure can include adding a pitch control additive comprising a non-talc pitch control additive component comprising a combination of clusters of calcite particles and composite fibers to a wood pulp furnish, thereby reducing an amount of talc-based pitch control additive component needed for pitch control in the papermaking process. Each composite fiber comprises a mineral attached to a fiber, wherein the mineral is at least 90 wt% based on the total weight of the composite fiber. The clusters of calcite particles have a specific surface area of about 1 .0 m2 / g to about 5.0 m2 / g. The pitch control additive comprises at least 20 wt% of the combination of the clusters of calcite particles based on the total weight of the pitch control additive

[0007] The composite fiber can include a nanocellulose fiber having calcium carbonate attached to the nanocellulose fiber. The calcium carbonate can have a scalenohedral structure.

[0008] The pitch control additive can be up to about 80wt% of the non-talc pitch control additive component based on the total weight of the pitch control additive.

[0009] The pitch control additive can be entirely composed of the non-talc pitch control additive.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A is a photograph of an experimental set-up for testing pitch control.

[0011] Figure 1 B is a close-up photograph of the experimental set-up of Figure 1A.

[0012] Figures 2A and 2B are surface contour plots of the pitch control testing.

[0013] Figure 2C is a three-dimensional surface contour plot of the pitch control testing.

[0014] Figure 3 are photographs of the pitch control analysis described in Example 1 .DETAILED DESCRIPTION

[0015] Talc is a common additive used in the papermaking industries for pitch control, however attempts are being made to limit talc utilization in the papermaking industry. Replacement of or even reduction of talc in papermaking has proven problematic, however, as a suitable replacement has not been found. Talc provides pitch control while having less negative impact on strength properties of the paper product as compared to other additives.Replacement of talc or even a reduction of the levels of talc with other common pitch control additives has been met with challenges in maintaining both pitch control and the needed strength properties. Methods of the disclosure surprisingly provide for a significant reduction of the amount of talc needed for pitch control, without sacrificing either pitch control performance or strength properties. In some embodiments, talc can be entirely replaced by a non-talc pitch control additive in accordance with the disclosure.

[0016] Methods of the disclosure comprise adding a pitch control additive that includes a nontalc pitch control additive component to a furnish as a replacement for at least a portion of a talc pitch control additive used in the process. The furnish can include, for example, wood pulp. The furnish can have any known composition including known wood pulps and thick stock additives. The non-pitch control additive component includes, at least, a composite fiber and / or precipitated calcium carbonate in the form of clusters of calcite particles. The composite fiber includes a mineral attached to a fiber. Use of both composite fibers and clusters of calcite particles in combination is contemplated herein, as well as the separate use of these additives. One or more other additive materials can also be included. For example, the non-talc pitch control additive component can include the composite fiber and a conventional calcium carbonate. Such a blend can be provided where the fiber itself includes calcium carbonate as the mineral attached to the fiber, and the conventional calcium carbonate is further calcium carbonate present in the additive. Other forms of calcium carbonate can be optionally included in addition to the composite fibers and / or clusters of calcite particles, such as, but not limited to, scalenohedral calcium carbonate, rhombohedral calcium carbonate, vaterite calcium carbonate, and aragonitic calcium carbonate. It has been surprisingly observed that the non-talc pitch control additive component, when including the composite fibers and / or clusters of calcite particles, is capable of adsorbing pitch from the furnish and preventing agglomeration of the pitch.

[0017] Methods of the disclosure can include adding both a talc-based pitch control additive component and a non-talc pitch control additive component to the furnish as the pitch control additive. The talc-based and non-talc components can be added separately, simultaneously, or as a premixed combination. For example, the non-talc pitch control additive can be added as a 50% replacement of the talc-based pitch control additive conventionally used, such that pitch control additive can include 50wt% of the non-talc pitch control additive component and 50wt% of the talc-based pitch control additive component. When used in combination, the amount of non-talc pitch control additive component can be up to 80wt%, up to 70wt%, up to 60wt%, up to50wt%, up to 40wt%, up to 30wt%, up to 25wt%, or at least 20 wt% based on the total weight of the pitch control additive. A remaining amount can be talc-based pitch control additive. For example, the pitch control additive can include about 20wt% to about 8wt0%, about 25wt% to about 50wt%, about 50wt% to about 80wt%, or about 40wt% to about 60wt% of the non-talc pitch control additive component based on the total weight of the pitch control additive. Any remaining amount can be, for example, talc-based pitch control additive. Entire replacement of the talc, such that the pitch control additive is entirely non-talc based pitch control additive is also contemplated herein. The talc-based pitch control additive can be talc or any known pitch control additive containing talc.

[0018] The non-talc pitch control additive component can include at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, at least 80 wt%, at least 90 wt% of the composite fiber and / or the clusters of calcite particles based on the total weight of the non-talc pitch control additive component. Other calcium carbonates can make-up a remaining amount of the non-talc pitch control additive. For example, the clusters of calcite particles, the composite fillers, or a combination thereof can be about 20 wt% to about 100 wt%, about 20 wt% to about 70 wt%, about 30 wt% to about 60 wt%, about 50 wt% to about 100 wt%, or about 25 wt% to about 75 wt% of the non-talc pitch control additive. For example, the non- talc pitch control additive component can be 100 wt% clusters of calcite particles, 100 wt% composite fibers, or 100 wt% of a combination of clusters of calcite particles and composite fibers.

[0019] Conventionally, non-talc minerals, such as conventional precipitated calcium carbonate, have not been found to be particularly good pitch control additives and were not capable of sufficiently removing pitch while maintaining strength properties to serve as a replacement for or even partial substitute for talc. It was conventionally thought that the platy nature of talc was necessary to provide for pitch fixing and strength advantages, and that minerals, such as precipitated calcium carbonate, without this platy structure could not effectively replace talc. It was commonly understood that calcium carbonate, while potentially providing better optical properties, was not a suitable talc replacement (or partial replacement) because it was not as efficient at adsorbing pitch and had more negative impact on strength as compared to talc.

[0020] Without intending to be bound by theory, it is believed that the composite fibers and clusters of calcite particles used in the methods of the disclosure as non-talc pitch control additive components can adsorb pitch and entrap pitch within the structure such that it can bemoved through the papermaking process without forming agglomerates or deposits on the as- formed paper or within the papermaking machine.

[0021] The non-talc pitch control additives, including composite fibers and / or clusters of calcite particles, can also provide enhanced strength properties to the paper product, thereby providing the needed balance between controlling pitch and maintaining strength performance needed to serve as an at least partial substitute for talc in the papermaking process. For example, it has been observed that enhanced strength can be achieved with a non-talc pitch control additive component containing composite fibers and clusters of calcite particles. Based on the knowledge regarding calcium carbonate addition, it was surprisingly found that the composite fibers, which can include calcium carbonate as the mineral attached to the fiber, as well as the clusters of calcite particles were capable of effectively adsorbing pitch, without negatively impacting strength, but in fact improving strength. Non-talc pitch additives containing a composite fiber and / or the clusters of calcite particles improved pitch fixing performance when replacing talc as compared to replacement with conventional calcium carbonate.

[0022] Pitch can be natural or synthetic. Pitch can include soluble organic matter originating from the extracts of wood, including fatty acids and esters, resins acids, and sterols, process additives such as defoamers, sizing agents, and coating. Natural pitch can be released from the wood pulp during chemical and mechanical pulping. Synthetic pitch can result from chemicals, such as latexes, present in the furnish. Pitch can generally be a sticky substance that can attach to papermaking machining causing downstream problems, such as depositing as impurities on the paper. Methods of the disclosure can effectively remove and / or reduce pitch using a pitch additive that is a combination of talc and a composite filler. Controlling pitch can allow for improved functioning of papermaking machines by reducing breakage caused by agglomeration of sticky impurities, improving paper quality by reducing holes, and reducing cleaning time and runnability problems by avoiding deposits in felts, fabrics and on cylinders in press and drying section.

[0023] Composite fibers for use in the pitch control additive in the methods of the disclosure can include a fiber and the mineral attached thereto. For example, the mineral is a non-talc mineral and can be in the form of long chains that attach to and surround the fiber, thereby coating the fiber. The composite fiber has at least 90 wt% mineral based on the total weight of the fiber. For example, the composite fiber can have about 0.05 wt% to about 10 wt% fiber based on the total weight of the composite fiber. Composite fibers can include those describedin International Patent Application Publication No. WO / 2023 / 192172, the disclosure of which is incorporated herein by reference in its entirety.

[0024] The method can utilize composite fibers where the mineral present on the fiber is calcium carbonate. The mineral can have a scalenohedral morphology. The fiber can be, for example, nanocellulose. The composite fiber can have a Horiba dg0of at least 20 pm. The composite fiber can have an average length of 100 pm to less than 300 pm.

[0025] The clusters of calcite particles for use in the non-talc pitch control additives of the disclosure can have a specific surface area of 1 .0 m2 / g to 5.0 m2 / g. The clusters can have average effective diameters of about 3.0 microns to 7.0 microns using a Horiba device. At least a portion of the particles in the clusters can have a prismatic morphology. As compared to commercially available conventionally produced calcium carbonates of the same particle size, the clusters of calcite particles in accordance with the disclosure can be 25% to 50% lower in BET surface area. Conventionally produced calcium carbonate is made by the standard industry practice of adding CO2 to the Ca(OH)2 slake. Conventionally produced calcium carbonates do not exhibit the cluster formation, resulting in a distinct structural form as compared to the clusters of calcite particles used in the methods of the disclosure.

[0026] The clusters can be made by known methods, such as described in International Patent Application Publication No. WO 1993 / 020010. For example, the clusters of calcite particles can be prepared by adding CO2 gas and calcium hydroxide slake to a reactor containing a water heal and calcium carbonate (PCC) in a reverse process in which the calcium hydroxide slake is added to the CO2. The ratio of the PCC seed and the slake to be added can be tuned to obtain a desired particle size. The rate of addition of the slake can be selected to maintain a conductivity between 50% and 80% saturation.

[0027] It has advantageously been found that the combination of the non-talc pitch control additives disclosed herein and talc can provide pitch control that is comparable to use of talc alone, while allowing a significant reduction of the amount of talc needed. The methods of reducing talc in pitch control of the disclosure allow for reduction of talc usage in papermaking processes without sacrificing pitch control or paper strength properties. For example, the non- talc pitch control additive can serve as a 50% replacement of talc as pitch control in a papermaking process. That is, in a papermaking process typically utilizing 100% talc for pitch control can reduce the reliance on talc to 50% talc and 50% non-talc pitch control additive based on the total weight of total pitch control additive. Other replacement amounts are also contemplated herein, including less than or greater than 50% replacement.

[0028] The non-talc pitch control additive component can include 100% composite fiber, 100% clusters of calcite particles, a mixture of composite fiber and clusters of calcite particles, or a mixture of composite fiber and / or clusters of calcite particles with other non-talc minerals. When other non-talc minerals are included with the composite fiber, the other non-talc minerals can be present in a form separate from the mineral attached to the composite fiber. For example, the non-talc pitch control additive component can include composite fiber and calcium carbonate. For example, the calcium carbonate can be in the form of a powder. For example, the non-talc additive can be an 80:20 to 20:80 blend of calcium carbonate to composite fiber. For example, the mineral of the composite fiber can be calcium carbonate when the composite fiber is blended with calcium carbonate. Use of other carbonates of alkaline earth metals are also contemplated for use in the non-talc pitch control additive component.

[0029] Methods making paper products can include addition of both a pitch control additive in accordance with the disclosure and fillers. Conventionally fillers and pitch control additives are added at different stages of the papermaking process. Typically pitch control additives are added upstream of the addition of filler. For example, in the paper making process the pitch control additive can be added in the furnish thick stock of the papermaking process. In contrast, traditional fillers, such as for optics and strength, are added after the thick stock is thinned and just prior to the thin stock being fed into the head box. Filler addition upstream in the furnish at the thick stock or in the pulping process would not be considered useful to enhance the paper’s optical properties as is traditional of a filler since the particle becomes worn and morphology changed as it passes through the paper making process.

[0030] Methods of the disclosure comprise adding the pitch control additive comprising the non-talc pitch control additive component to the furnish or at the pulping stage and upstream of any addition of filler. The method can include, for example, adding the pitch control additive to the wood pulp furnish to form a thick stock that has a solids content of at least 1%. The thick stock can then be diluted, for example, with white water to form a thin stock to which filler is then added. The thin stock is diluted to a lower fiber content than the thick stock and typically has a solids content of less than 1%.EXAMPLESExample 1 : Non-talc additive comprising composite fibers

[0031] A 2% solids papermaking furnish using Bleached Hardwood was prepared in a deflaker apparatus. The mixture was diluted to a 1% solids and then 0.2 wt% (0.2 kg / ton dose) of latex was added (0.2 wt% on a dry fiber equivalent). The pitch control additive was then added to the mixture. Table 1 below shows the amounts of talc replacement tested and compositions of the non-talc pitch control additive, as well as the comparative results among the tested samples and a sample using 100% talc. In the samples tested, the composite fiber used in the non-talc pitch control additive component tested were nanocellulose fibers having scalenohedral calcium carbonate attached thereto. The calcium carbonate (LO Calcium Carbonate) is a commercially available calcium carbonate sold under the tradename Albacar® LO Precipitated Calcium Carbonate (Minerals Technology Inc.)

[0032] The pitch control achieved was tested by adhering a 3 cm x 4 cm section of aluminum foil to the bottom of a 1 -liter beaker as shown in Figures 1A and 1 B. 600 ml of the pulp furnish mixture was added to the beaker with the aluminum therein and stirred at 400 rpm for one hour. The aluminum foil was removed and dried at 105 °C for 10 min.

[0033] The pitch test analysis was performed by taking a picture of the aluminum foil after drying and counting the number of agglomerates (stickies) per cm2. The test showed the number of large agglomerates that would have been stuck on the paper machine and not left the system with the paper, with a large number of agglomerates (“stickies”) being undesirable.Table 1 : Pitch Testing Analysis*wt% in Table 1 are based on the total weight of pitch control additive, including talc and nontalc pitch control additives.

[0034] Figures 2A to 2C show contour plots of the pitch testing analysis. Images, which were taken during the pitch control testing to count the number of stickies, are shown in Figure 3. Figure 3 shows images of samples tested with pitch control additions of 100% talc, 50:50 talc:calcium carbonate, 50:50 talc:composite fiber, 50:50 talc:non-talc pitch control additive, with the non-talc pitch control additive being an 80:20 mixture of calcium carbonate:composite fiber, and 50:50 talc:non-talc pitch control additive, with the non-talc pitch control additive being a 67:33 mixture of calcium carbonate:composite fiber. It was surprisingly and beneficially found that replacement of up to 50% of talc with the composite fiber was possible without sacrificing pitch control. The composite fiber was capable of replacing a portion of the talc while maintaining pitch control, and improving bulk strength, tensile strength, and Scott Bond properties of the material as compared to the use of talc alone as the pitch control additive. The pitch control provided by the partial replacement of talc with the composite fiber was surprising as the addition of LO calcium carbonate with talc was found to reduce pitch control as compared to talc alone. Further, it was found that a non-talc pitch control additive including the composite fiber and calcium carbonate was capable of replacing 50% of talc with improved pitch control over a 50% replacement of talc with the LO calcium carbonate alone.Example 2: Non-Talc Additive Comprising Clusters of Calcite Particles

[0035] A similar pitch test was performed as described in Example 1 using the clusters of calcite particles. It was surprisingly found that the clusters of calcite particles alone and in a 50% talc 150% clusters of calcite particles performed better than the traditional LO calcium carbonate. It was observed that 50% of the talc could be replaced with the clusters of calcite particles, while maintaining the same pitch control as the sample having 100% talc.

[0036] Modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compositions and methods pertain having the benefit of the teachings presented in the foregoing descriptions. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0037] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term “comprising” can include the aspect of “consisting of.” Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compositions and methods belong. In this specification and in the claims which follow, reference will be made to a number of terms which shall be defined herein.

[0038] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present disclosure. Any recited method can be carried out in the order of events recited or in any other order that is logically possible.

[0039] The use of the terms “a,” “an,” “the,” and similar referents in the context of the disclosure herein (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated. Recitation of ranges of values herein merely are intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended to better illustrate the disclosure herein and is not a limitation on the scope of the disclosure herein unless otherwise indicated. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure herein.

Claims

What is claimed is:1 . A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process, comprising: adding a pitch control additive to a wood pulp furnish, wherein the pitch control additive comprises a non-talc pitch control additive component comprising composite fibers, thereby reducing an amount of talc-based pitch control additive component needed for pitch control in the papermaking process, wherein: the composite fibers adsorb pitch from the wood pulp furnish and prevent agglomeration of pitch particles, each composite fiber comprises mineral attached to a fiber, wherein the mineral is at least 90 wt% based on the total weight of the composite fiber, and the pitch control additive comprises at least 20 wt% of the composite fibers based on the total weight of the pitch control additive.

2. The method of claim 1 , wherein the pitch control additive comprises up to 50wt%, or up to about 80wt%, of the non-talc pitch control additive component, based on the total weight of the pitch control additive, with the remaining amount being the talc-based pitch control additive component.

3. The method of claim 1 or 2, wherein the non-talc pitch control additive component further comprises calcium carbonate particles.

4. The method of claims 1 or 2, wherein the non-talc pitch control additive component comprises an 80:20 to 20:80 blend of calcium carbonate particles and composite fiber.

5. The method of any one of claims 1 to 4, wherein the non-talc pitch control additive component further comprises clusters of calcite particles6. The method of claim 5, wherein the clusters of calcite particles have a surface area of about 1 .0 m2 / g to about 5.0 m2 / g.

7. The method of any one of the preceding claims, wherein the mineral is calcium carbonate and the fiber is nanocellulose.

8. The method of any one of the preceding claims, wherein the composite fibers have a Horiba dg0of at least 20 pm.

9. The method of any one of the preceding claims, wherein the composite fibers have an average length of 100 pm to less than 300 pm.

10. The method of any one of the preceding claims, wherein the composite fibers comprise nanocellulose as the fiber.11 . The method of any one of the preceding claims, wherein the mineral has a scalenohedral morphology.

12. The method of any one of the preceding claims, comprising adding the non-talc pitch control additive component to the furnish separately from the talc-based pitch control additive component.

13. The method of any one of the preceding claims, comprising premixing the pitch control additive comprising a non-talc pitch control additive component and a talc-based pitch control additive component and adding the premixed pitch control additive to the furnish.

14. The method of any one of the preceding claims, wherein the wood pulp furnish comprising the pitch control additive having a solids content of at least 1%.

15. The method of claim 14, further comprising diluting the wood pulp furnish comprising the pitch control additive to a thin stock comprising less than 1% solids, and adding a filler to the thin stock.

16. The method of claim 15, wherein the filler comprises calcium carbonate17. A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process, comprising: adding a pitch control additive comprising a non-talc pitch control additive component comprising a precipitated calcium carbonate to a wood pulp furnish, thereby reducing an amount of talc-based pitch control additive component needed for pitch control in the papermaking process, wherein: the precipitated calcium carbonate comprises clusters of calcite particles with a specific surface area of about 1 .0 m2 / g to about 5.0 m2 / g, andthe pitch control additive comprises at least 20 wt% of the clusters of calcite particles based on the total weight of the pitch control additive.

18. The method of claim 17, wherein the calcite particles comprise particles having a prismic morphology.

19. The method of claim 17 or 18, wherein the clusters have an average effective diameter of about 3.0 microns to about 7.0 microns.

20. The method of any one of claims 17 to 19, wherein the pitch control additive comprises up to 50wt%, or up to about 80wt%, of the non-talc pitch control additive component, based on the total weight of the pitch control additive, with the remaining amount being the talcbased pitch control additive component.21 . The method of any one of claims 17 to 20, comprising premixing the talc-based pitch control additive component and the non-talc pitch control additive component to form a premixed pitch control additive and adding the premixed pitch control additive to the furnish.

22. The method of any one of claims 17 to 20, wherein the pitch control additive comprises a non-talc pitch control component and a talc-based pitch control component, and the non-talc pitch control component is added separately to the furnish from the talc-based pitch control additive component.

23. The method of any one of claims 17 to 22, wherein the wood pulp furnish comprising the pitch control additive having a solids content of at least 1%.

24. The method of any one of claims 23, further comprising diluting the wood pulp furnish comprising the pitch control additive to a thin stock comprising less than 1% solids, and adding a filler to the thin stock.

25. The method of claim 24, wherein the filler comprises calcium carbonate.

26. A method for reducing an amount of talc-based pitch control additive used for pitch control in a papermaking process, comprising: adding a pitch control additive comprising a non-talc pitch control additive component comprising a combination of clusters of calcite particles and composite fibers to a wood pulp furnish, thereby reducing an amount of talc-based pitch control additive component needed for pitch control in the papermaking process, wherein:each composite fiber comprises mineral attached to a fiber, wherein the mineral is at least 90 wt% based on the total weight of the composite fiber, the clusters of calcite particles have a specific surface area of about 1 .0 m2 / g to about 5.0 m2 / g, and the pitch control additive comprises at least 20 wt% of the combination of the clusters of calcite particles and the composite fibers based on the total weight of the pitch control additive.

27. The method of claim 26, wherein the calcite particles comprise particles having a prismic morphology.

28. The method of claim 26 or 27, wherein the clusters have an average effective diameter of about 3.0 microns to about 7.0 microns.

29. The method of any one of claims 26 to 28, wherein the pitch control additive comprises up to 50wt%, or up to about 80wt%, of the non-talc pitch control additive component, based on the total weight of the pitch control additive, with the remaining amount being the talcbased pitch control additive component.

30. The method of any one of claims 26 to 29, comprising premixing the talc-based pitch control additive component and the non-talc pitch control additive component to form a premixed pitch control additive and adding the premixed pitch control additive to the furnish.31 . The method of any one of claims 26 to 30, wherein the pitch control additive comprises a non-talc pitch control component and a talc-based pitch control component, and the non-talc pitch control component is added separately to the furnish from the talc-based pitch control additive component.

32. The method of any one of claims 26 to 31 , wherein the wood pulp furnish comprising the pitch control additive has a solids content of at least 1%.

33. The method of claim 32, further comprising diluting the wood pulp furnish comprising the pitch control additive to a thin stock comprising less than 1% solids, and adding a filler to the thin stock.

34. The method of claim 33, wherein the filler comprises calcium carbonate.

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