Method for measuring the pitch size of pulp slurry, method for calculating the pitch content, system, program, and apparatus.

Abstract

The objective is to provide a method for observing the entire pitch in a pulp slurry, measuring the pitch size, and calculating the pitch content. [Solution] A method for measuring the pitch size in a pulp slurry, comprising: adding a pitch staining agent to a pulp slurry to obtain a pulp slurry containing stained pitch; a three-dimensional observation image acquisition step of observing the pulp slurry containing the stained pitch in three dimensions and obtaining a three-dimensional observation image of the pulp slurry; and a pitch size measurement step of analyzing the three-dimensional observation image using image analysis software and measuring the size of the observed stained pitch.

Description

Technical Field

[0001] The present invention relates to a method for measuring the pitch size of a pulp slurry, a method for calculating the pitch content, a system, a program, and an apparatus.

Background Art

[0002] Conventionally, in the papermaking process, problems caused by pitch have occurred, and various chemicals have been developed to suppress and prevent these problems. Pitch refers to a water-insoluble adhesive substance mainly composed of organic substances derived from natural resins and gum substances released from wood, pulp, and paper, as well as additives used in the manufacturing process of paper and pulp.

[0003] Generally, pitch is dispersed in a colloidal state in the process water (pulp slurry or white water) in the manufacturing process of paper and pulp. However, due to some external actions, such as a large shear force, a sudden change in pH, or an excessive addition of a sulfate band (aluminum sulfate), its colloidal state is destroyed, and it is considered to aggregate and grow larger. This aggregated and enlarged pitch adheres not only to paper, pulp, and manufacturing equipment such as fan pumps, pipes, chests, wires, felts, and rolls due to its adhesiveness, but also the adhered substances peel off and reattach to paper and pulp. Then, the formed paper stains and defects reduce the quality of paper products, and the resulting paper breaks cause problems such as reducing productivity and workability.

[0004] In recent years, due to the diversification of paper, the types and amounts of additives used have increased, the use ratio of waste paper has increased, and the use of lower-grade waste paper has increased, as well as the progress of the reuse of water used in the papermaking process. As a result, the occurrence of pitch problems has increased more than ever, and the occurrence form has become more complicated. For example, problems with pitch originating from recycled paper materials are increasing, not only from conventional mechanical pulps such as grand pulp (GP) and thermomechanical pulp (TMP), and from chemical pulps such as kraft pulp (KP). Examples of pitch originating from recycled paper materials include synthetic resins such as magazine spine glue (polyvinyl acetate) and labels (acrylic adhesive). Furthermore, in order to improve productivity, the enlargement of equipment and the increase in papermaking speed, combined with other factors, have led to the emergence of pitch contamination problems on the wire section, press section rolls, blankets, and blanket suction boxes.

[0005] To suppress such pitch problems, several methods have been proposed and put into practical use, including methods of adsorbing pitch components onto inorganic compounds such as fine talc, methods of fixing pitch particles to pulp fibers before aggregation, methods of dispersing pitch particles, and methods combining these. All of these methods utilize pitch control agents, and compounds appropriate to each method are used as pitch control agents.

[0006] Pitch control agents are chemicals added to the water used in the paper and pulp manufacturing process (pulp slurry and white water) to control the pitch. Methods for monitoring the pitch in pulp slurry and white water are being studied to determine the amount of these agents to use. For example, Patent Document 1 describes a method for determining the amount of hydrophobic contaminants in the papermaking process using fluorescent dyes, a method for evaluating treatment chemicals to control hydrophobic contaminants using fluorescent dyes, and a method for optimizing the amount of treatment chemicals to reduce hydrophobic contaminants in the papermaking process using fluorescent dyes. It describes determining the amount of hydrophobic contaminants (i.e., pitch, etc.) in the papermaking process by coloring them with fluorescent dyes and measuring the fluorescence of these dyes.

[0007] Furthermore, Patent Document 2 discloses a method for monitoring one or more types of hydrophobic contaminants (i.e., pitch, etc.) in a papermaking process, which includes the following steps: (a) obtaining a fluid sample from the papermaking process; (b) selecting a hydrophobic dye that interacts with the contaminants in the fluid and is capable of fluorescing in the fluid; (c) adding the dye to the fluid and allowing it to stand for a sufficient amount of time for the dye to interact with the contaminants in the fluid; (d) measuring the fluorescence of the dye in the fluid; (e) relating the fluorescence of the dye to the concentration of the contaminants; and (f) optionally controlling the amount of one or more chemical agents added to the papermaking process to suppress or inactivate the contaminants.

[0008] Furthermore, Patent Document 3 describes a method for detecting organic impurities in pulp and fibers using hydrophobic dyes such as fluorescent dyes, and Patent Document 4 describes a method for measuring the concentration of hydrophobic organic particles in the filtrate of paper stock, characterized by marking the hydrophobic organic particles with a fluorescent dye, subsequently exciting these particles to cause them to emit light, detecting the light emitted by the marked particles, and then measuring the mass concentration of the particles from the fluorescence intensity. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Special Publication No. 2016-535244 [Patent Document 2] Patent No. 5762394 [Patent Document 3] Special Publication No. 2010-529421 [Patent Document 4] Special Publication No. 2010-520444 [Overview of the project] [Problems that the invention aims to solve]

[0010] As described above, a method for detecting pitch in pulp slurry during the papermaking process using fluorescence measurement technology has been disclosed. However, in observing pitch, components other than pitch in the pulp slurry (e.g., pulp fibers or enlarged inorganic matter) have been removed beforehand. This is because if pitch is obscured by pulp fibers in the pulp slurry, it will be difficult to observe the pitch. Therefore, for example, even within the pitch in the pulp slurry, enlarged pitch that has adhered to pulp fibers has been removed before observation, and it has not been possible to accurately observe the entirety of pitch in the pulp slurry.

[0011] The present invention has been made in view of the above-mentioned problems, and aims to provide a method for observing the entire pitch in a pulp slurry, measuring the pitch size, and calculating the pitch content. Furthermore, the present invention aims to provide a system, program, and apparatus for measuring the pitch size in a pulp slurry or for calculating the pitch content in a pulp slurry. [Means for solving the problem]

[0012] The inventors of this invention conducted extensive research to solve the above problems and, as a result, discovered an observation method that allows for the observation of pitch in pulp slurry in the papermaking process in three dimensions, even when the pitch is hidden behind pulp fibers, thereby enabling the acquisition of more accurate pitch information in the pulp slurry. This led to the completion of the present invention.

[0013] In other words, the present invention provides the following: [1] A method for measuring the pitch size in a pulp slurry, comprising the steps of: adding a pitch staining agent to a pulp slurry to obtain a pulp slurry containing stained pitch; a three-dimensional observation image acquisition step of observing the pulp slurry containing the stained pitch in three dimensions and obtaining a three-dimensional observation image of the pulp slurry; and a pitch size measurement step of analyzing the three-dimensional observation image using image analysis software and measuring the size of the observed stained pitch. [2] The pitch size measurement method according to [1] above, wherein the step of acquiring a three-dimensional observation image is to acquire a three-dimensional observation image of a pulp slurry including stained pitch and pulp fibers, and the image analysis in the pitch size measurement step includes removing the image of pulp fibers from the three-dimensional observation image. [3] The pitch size measurement method according to [1] or [2] above, wherein the pitch staining agent is a fluorescent staining agent, and the step of acquiring a three-dimensional observation image comprises sequentially changing the wavelength of fluorescence detection to capture a planar image of the pulp slurry obtained from a fluorescence microscope at each detection wavelength, and generating a three-dimensional observation image based on the planar image to acquire a three-dimensional observation image of the pulp slurry. [4] A method for calculating pitch content, comprising a pitch content calculation step of calculating the pitch content in a pulp slurry from the size of the stained pitch obtained by any of the pitch size measurement methods described in [1] to [3] above. [5] A system comprising a 3D observation image acquisition unit that observes a pulp slurry containing staining pitch in a three-dimensional direction and acquires a 3D observation image of the pulp slurry, and a pitch size measurement unit that analyzes the 3D observation image using image analysis software and measures the size of the observed staining pitch. [6] The system according to [5], further comprising a pitch content calculation unit that calculates the pitch content in the pulp slurry from the size of the stained pitch measured by the pitch size measurement unit. [7] A program that causes a computer to function as a 3D observation image acquisition unit and a pitch size measurement unit, wherein the 3D observation image acquisition unit acquires a 3D observation image of the pulp slurry obtained by observing the pulp slurry including the stained pitch in a three-dimensional direction, and the pitch size measurement unit analyzes the 3D observation image using image analysis software to measure the size of the observed stained pitch. [8] The program described in [7] above, wherein the computer further functions as a pitch content calculation unit, and the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the stained pitch measured by the pitch size measurement unit. [9] A device comprising a 3D observation image acquisition unit and a pitch size measurement unit, wherein the 3D observation image acquisition unit acquires a 3D observation image of the pulp slurry obtained by observing the pulp slurry including the staining pitch in a 3D direction, and the pitch size measurement unit analyzes the 3D observation image using image analysis software to measure the size of the observed staining pitch.

[10] The apparatus according to [9], further comprising a pitch content calculation unit, wherein the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the stained pitch measured by the pitch size measurement unit. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a method for observing the entire pitch in a pulp slurry, measuring the pitch size, and calculating the pitch content. Furthermore, according to the present invention, it is possible to provide a system, program, and apparatus for measuring the pitch size in a pulp slurry or for calculating the pitch content in a pulp slurry. [Brief explanation of the drawing]

[0015] [Figure 1] This figure shows an example of a pulp slurry containing dyed pitch and pulp fibers. [Figure 2](a) An example of a three-dimensional image composed of a plurality of planar images obtained by changing the received light wavelength and photographing a pulp slurry with a fluorescence microscope, and (b) a planar image in the three-dimensional direction (Z = z(2)) of (a). [Figure 3] A diagram for explaining (a) the maximum diameter and (b) the minimum diameter of the pitch. [Figure 4] A schematic diagram of a pitch content calculation system according to an embodiment of the present invention. [Figure 5] A block diagram showing the overall configuration of a pitch content calculation device according to an embodiment of the present invention. [Figure 6] An observation image obtained by an optical fluorescence microscope in Example 1 is shown. [Figure 7] An observation image obtained by an automatic cell counter in Comparative Example 1 is shown. [Embodiments for Carrying Out the Invention]

[0016] Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention.

[0017] [Method for Measuring Pitch Size] The present invention is a method for measuring the pitch size in a pulp slurry, which includes the steps of adding a pitch staining agent to the pulp slurry to obtain a pulp slurry containing stained pitch, performing observation of the pulp slurry containing the stained pitch in a three-dimensional direction to obtain a three-dimensional observation image of the pulp slurry (three-dimensional observation image acquisition step), and performing image analysis on the three-dimensional image observation image using image analysis software to measure the size of the observed stained pitch (pitch size measurement step).

[0018] The present invention provides a method for measuring pitch size, which involves staining the pitch contained in a pulp slurry, observing it in three dimensions, and measuring the size of the stained pitch using the three-dimensional observation image. According to the present invention, since the pitch contained in the pulp slurry is observed while the pulp fibers are present in the pulp slurry, it is also possible to observe the pitch adhering to the pulp fibers, and the pitch size can be measured over the entire area of ​​the pitch contained in the pulp slurry, thereby improving the accuracy of measuring the pitch size contained in the pulp slurry. Furthermore, since it is possible to observe the pitch in the pulp slurry while pulp fibers are still present, the pulp slurry can be observed and measured in real time, or immediately after sampling the sample to be measured. This allows for the measurement of the overall pitch in the pulp slurry while suppressing the effects of changes in pitch over time. As a result, it is possible to observe the pitch in the pulp slurry in a more accurate manner, reflecting the state of pitch in the papermaking process, and to quickly measure the pitch size in the pulp slurry.

[0019] The "pulp slurry" in this invention is not particularly limited and can be any pulp slurry obtained by suspending papermaking raw materials in water, and which contains pulp fibers and pitch components. The papermaking raw materials are not particularly limited and can be, for example, wood pulp (chemical pulp, mechanical pulp, etc.), recycled paper, coated waste paper, etc.

[0020] In this invention, "pitch" refers to the pitch in the papermaking process, and in one embodiment, it refers to an adhesive substance formed by the aggregation and agglomeration of resins contained in the papermaking raw materials. Examples of resins in one or more embodiments include natural resin components contained in wood pulp, fatty acids or their salts, adhesives used in magazine spine glue and labels mixed in from recycled paper raw materials, synthetic resins such as beeswax and paraffin wax.

[0021] The pitch stain added to the pulp slurry can be any stain that stains pitch. Pitch is a hydrophobic adhesive, while pulp fibers are hydrophilic. Therefore, by using a hydrophobic dye, it is possible to selectively stain the pitch in the pulp slurry. Specific examples of hydrophobic dyes for staining pitch include fluorescent stains such as Fluorol 555, Nile Red, and Acridine Orange, as well as Sudan IV. Of these, those that produce a strong contrast are preferred for ease of observation, and fluorescent stains such as Fluorol 555 and Nile Red, which are yellow-orange, are preferably used.

[0022] From the viewpoint of rapid dyeing, the above hydrophobic dye is preferably dissolved in an organic solvent and added to the pulp slurry. From the viewpoint of rapid dispersion in the aqueous pulp slurry, it is preferable to use a hydrophilic organic solvent, such as ethanol, propanol, or tetrahydrofuran, and ethanol is particularly preferred.

[0023] The amount of pitch staining agent added is not particularly limited and should be adjusted as appropriate depending on the pitch content in the pulp slurry. However, it is sufficient to add an amount and concentration that allows the staining of the pitch to be clearly visible, and it is not advisable to add more than necessary for image observation. Typically, it is added at a dye concentration of 0.001 to 10 mg / L.

[0024] The location and method of adding the pitch dye to the pulp slurry are not particularly limited. It may be added to the raw material line (the line through which the pulp slurry moves) in the papermaking process, or to the white water. Alternatively, a separate measuring line branching off from the raw material line may be installed, and the pitch dye may be added to the measuring line. For example, when the pitch dye is added to the pulp slurry in the raw material line, it is preferable to add the pitch dye to the pulp slurry in at least one of the devices that apply mechanical shear to the pulp slurry, and / or to the pulp slurry upstream of the aforementioned device. A device that applies mechanical shear refers to, for example, a device that agitates the pulp slurry at a rotational speed of 50 rpm to 3000 rpm within the device, where the stress acting on the pulp slurry within the device is greater than the stress acting on the pulp slurry flowing through the piping. Specifically, examples include pulpers, refiners, screw presses, double separators, refining screens, rotary screens, washers, thickeners, and fan pumps. Preferred specific devices include pulpers, refiners, and fan pumps.

[0025] (3D observation image acquisition step) For observing a pulp slurry containing stained pitch stained with the above-mentioned pitch stain, a microscope or a fluorescence microscope can be used, for example. When observing the pulp slurry using a fluorescence microscope, a fluorescent stain is used as the pitch stain. As a method for observing the pulp slurry in three dimensions and obtaining a three-dimensional observation image of the pulp slurry, for example, by sequentially changing the fluorescence detection wavelength, planar images obtained from the fluorescence microscope at each detection wavelength are captured, and a three-dimensional observation image is generated based on the planar images, thereby allowing observation of the pulp slurry containing stained pitch in three dimensions and obtaining a three-dimensional observation image of the pulp slurry. The method for observing a pulp slurry containing stained pitch in three dimensions is not limited to the above method, and an appropriate method can be adopted as appropriate. For example, a method may be used in which a pulp slurry containing stained pitch is observed using a fluorescence microscope, and a three-dimensional observation image of the stained pitch is generated by generating point cloud data by calculating the positional information of the fluorescent substance contained in the stained pitch, thereby observing the pulp slurry in three dimensions. It is preferable to capture the observation images with a CCD camera or digital camera for image analysis. Furthermore, while higher magnification and image size generally lead to higher accuracy, they are not particularly limited; as long as the image is large enough to be processed during subsequent image analysis, it is sufficient.

[0026] In the above 3D observation image acquisition step, it is sufficient to observe the pulp slurry including the stained pitch at one or more locations in the 2D direction, and then observe the 3D direction at two or more locations at the observation points determined in the 2D direction. The magnification of the microscope used for observation is preferably 4 to 20 times. This is because observing the pulp slurry under the above conditions can further improve the accuracy of calculating the pitch content in the pulp slurry.

[0027] The above 3D observation image acquisition step may include a preliminary step of taking a sample of the pulp slurry to be observed and adding a thickening agent. Including such a preliminary step suppresses the flow of stained pitch and pulp in the pulp slurry, which is the object of observation, when acquiring a 3D observation image of the pulp slurry in the 3D observation image acquisition step, thereby enabling the acquisition of a more accurate 3D observation image. The thickening agent is not particularly limited, and any component that suppresses the flowability of the pulp slurry and does not affect the acquisition of the 3D observation image, such as agar or gelatin, can be selected.

[0028] In the three-dimensional observation image acquisition step described above, it is preferable to observe the pulp slurry including the stained pitch within a range where the number of pitches in the three-dimensional observation image is between 50 and 1000. This is because it further improves the accuracy of calculating the pitch content in the pulp slurry and the pitch content ratio.

[0029] (Pitch size measurement step) The 3D observation image of the pulp slurry, including the stained pitch, obtained from the 3D observation image acquisition step, is analyzed on a computer using image analysis software. In the image analysis, the stained pitch in the 3D observation image is identified, and the size of each observed stained pitch is measured.

[0030] The image analysis software used in the present invention is not particularly limited as long as it is capable of performing image analysis processing on 3D observation images. For example, PRECiV and Sellsens from OLYMPUS Corporation; WinROOF from Mitani Corporation; and BZ-H1A (analysis application) from Keyence Corporation can be suitably used.

[0031] For example, in the pitch size measurement step, the average size D of the stained pitch P in the 3D observation image can be calculated using image analysis software. The average size D is the average diameter of the pitch P in the XY plane in the 3D observation image, as shown in Figure 3(a). For example, the image analysis software used in the image analysis of the pitch size measurement step can measure the diameter in the XY plane at multiple points in the 3D direction Z of the stained pitch P to be measured in the 3D observation image, and calculate the average size D of the stained pitch P in the XY plane. In addition to calculating the average size D of the stained pitch P in the XY plane in the 3D observation image using image analysis software, the maximum and minimum diameters of the stained pitch P in the XY plane can also be measured using image analysis software.

[0032] Furthermore, in the pitch size measurement step, for example, the average size D' of the stained pitch P in the 3D observation image can be calculated using image analysis software. The average size D' is the average diameter of the pitch P in the 3D observation image in the XZ plane, including the 3D direction Z, as shown in Figure 3(b). For example, the image analysis software used in the image analysis of the pitch size measurement step can measure the diameter on the XZ plane at multiple points in the Y direction of the stained pitch P to be measured in the 3D observation image, and calculate the average size D' of the stained pitch P on the XZ plane. In addition, in the pitch size measurement step, the image analysis software can not only calculate the average size D' of the stained pitch P in the XZ plane in the 3D observation image, but also measure the maximum and minimum diameters of the pitch P on the XZ plane. Furthermore, although not shown in the figure, for example, the image analysis software used in the image analysis of the pitch size measurement step can measure the diameter on the YZ plane at multiple points in the X direction of the stained pitch P to be measured in the 3D observation image, and calculate the average size D'' of the stained pitch P on the YZ plane. Furthermore, in the pitch size measurement step, image analysis software can be used not only to calculate the average size D'' of the staining pitch P in the YZ plane within the 3D observation image, but also to measure the maximum and minimum diameters of the staining pitch P in the YZ plane.

[0033] Furthermore, in the pitch size measurement step, image analysis software can be used to measure not only the diameter of the stained pitch P in the 3D observation image, but also, for example, the radius, equivalent circle diameter, longest diameter, shortest diameter, outer circumference, area, surface area, volume, etc. If it is necessary to set a direction when measuring the size of the stained pitch P in the 3D observation image, an appropriate direction can be set as needed according to the indicator to be measured (for example, diameter, radius, equivalent circle diameter, longest diameter, shortest diameter, outer circumference, surface area, volume, etc.). In addition, the above indicators can be selected according to the shape of the pitch being measured; for example, if the pitch shape has a short axis and a long axis, the average of these can be used as the diameter.

[0034] Preferably, the size of the staining pitch described above is obtained by measuring at least one of the maximum, minimum, and average values ​​of at least one indicator selected from the diameter, radius, equivalent circle diameter, longest diameter, shortest diameter, outer circumference, area, surface area, and volume of each staining pitch identified from the 3D image. Preferably, the indicator for measuring the pitch size of the staining pitch is determined based on the amount of information in the 3D image obtained in the 3D image observation step. In this invention, the size of the observed staining pitch obtained in the pitch size measurement step does not need to be a precisely measured size, but rather a size that can be calculated based on at least one indicator selected from the diameter, radius, equivalent circle diameter, longest diameter, shortest diameter, outer circumference, area, surface area, and volume of the staining pitch measured by the image analysis software used in the pitch size measurement step.

[0035] In the pitch size measurement step of the present invention, it is preferable to perform image analysis on a 3D observation image using image analysis software to measure the diameter, equivalent circle diameter, longest diameter, and outer circumference (also called the perimeter) of the observed stained pitch, and it is more preferable to measure the maximum values ​​of the diameter, equivalent circle diameter, longest diameter, and outer circumference of the stained pitch.

[0036] In the pitch size measurement step of the present invention, it is preferable to measure not only the size of the stained pitch but also the number of stained pitches. By measuring the number of stained pitches in addition to the size of the stained pitches included within the range of the 3D observation image, when calculating the pitch content in the pulp slurry from the size of the stained pitches obtained by the pitch size measurement method of the present invention, it is possible to add information on the number of pitches in addition to the pitch size, thereby further improving the accuracy of calculating the pitch content in the pulp slurry.

[0037] In the pitch size measurement step of the present invention, it is preferable to map the stained pitches identified from the 3D observation image during image analysis and measure the distance between each stained pitch. By measuring the distance between stained pitches in addition to the size of the stained pitches contained in the 3D observation image, when calculating the pitch content in the pulp slurry from the size of the stained pitches obtained by the pitch size measurement method of the present invention, it is possible to add distance information between pitches in the pulp slurry in addition to the pitch size, thereby further improving the accuracy of calculating the pitch content in the pulp slurry and the amount of pitch aggregated.

[0038] (Removal of pitch fibers in image analysis) In the present invention, the above-described step of acquiring a three-dimensional observation image is also the step of acquiring a three-dimensional observation image of a pulp slurry containing dyed pitch and pulp fibers. In the image analysis in the pitch size measurement step, it is preferable to remove the image of pulp fibers from the three-dimensional observation image of the pulp slurry containing dyed pitch and pulp fibers. By removing pulp fibers that are not the object of observation from the three-dimensional observation image, the accuracy of pitch size measurement in the pitch size measurement step is improved, and the accuracy of calculating the pitch content in the pulp slurry in the subsequent pitch content calculation step can be further improved. Although pulp fibers can be observed without dyeing, depending on the papermaking raw materials used in the pulp slurry, the three-dimensional image of pulp fibers in the pulp slurry may become unclear. In that case, it is preferable to dye the pulp fibers with a dye before performing the three-dimensional observation image acquisition step to acquire a three-dimensional observation image of the pulp slurry containing dyed pitch and dyed pulp fibers.

[0039] In the present invention, when dyes are used to color pulp fibers, the dyes are not particularly limited as long as they are hydrophilic dyes that color hydrophilic pulp fibers. For example, direct dyes, acid dyes, basic dyes, reactive dyes, sulfur dyes, and fluorescent dyes can be used, and it is preferable to use at least one selected from the group consisting of these.

[0040] The pitch size measurement method of the present invention is not particularly limited to pulp slurry or white water in the papermaking process, but is preferably applied to pulp slurry at the pulper outlet raw material, unbleached raw material, adjusted raw material, etc., in the pulp manufacturing process, or white water circulating within the process, or pulp slurry or white water before and after chemical treatment, or pulp slurry or white water immediately after physical shear has been added. One or more embodiments of the above pulp manufacturing process include a pulp manufacturing process that produces pulp by reusing waste paper (including a pulper process and a deinking process), and a pulp manufacturing process that produces pulp from coniferous and hardwood chips (including a digestion process and an unbleached pulp washing process performed after the digestion process).

[0041] The pitch size measurement method of the present invention may include a step of removing pulp fibers with a major axis of 150 μm or more from among the pulp fibers in the pulp slurry before the step of acquiring a three-dimensional observation image. According to the method of the present invention, the pitch content in the pulp slurry can be calculated even when pulp fibers are present in the pulp slurry, and accuracy in calculating the pitch content in the pulp slurry can be maintained without observing the pitch attached to pulp fibers with a major axis of 150 μm or more. Therefore, even when the method of the present invention is applied to a pulp slurry containing pulp fibers with a major axis of less than 150 μm, accuracy in calculating the pitch content in the pulp slurry can be maintained.

[0042] Furthermore, a method for calculating pitch content, which includes a pitch content calculation step of calculating the pitch content in a pulp slurry from the size of the stained pitch obtained by the pitch size measurement method of the present invention described above, is also one embodiment of the present invention.

[0043] (Pitch content calculation step) The pitch content in the pulp slurry can be calculated by determining the total pitch content within the observation range by summing the sizes of each stained pitch measured in the pitch size measurement step. In this invention, the pitch content in the pulp slurry may also represent the pitch content (volume %) in the pulp slurry. For example, the pitch content (%) in the pulp slurry is calculated by subtracting the amount of pulp slurry in the observation range from the total pitch content in the observation range. Regarding the pitch content (%) in the pulp slurry, for example, if the size of each stained pitch measured in the pitch size measurement step is the area in a specific direction, the pitch content (%) in the pulp slurry in a specific direction within the observation range can be calculated by subtracting the area in that specific direction within the observation range of the pulp slurry from the sum of the pitch sizes (areas) in that specific direction within the observation range. In this case, a more specific pitch content (%) in the pulp slurry can be calculated by calculating the pitch content (%) in multiple directions. Furthermore, for example, if the size of each stained pitch measured in the pitch size measurement step is the pitch volume, the pitch content (%) in the pulp slurry can be calculated by subtracting the volume of the observed area of ​​the pulp slurry from the total volume of pitch content in the observed area.

[0044] The pitch content calculation step of the present invention can calculate the pitch content in a pulp slurry by size. For example, if the average value of the equivalent circle diameter is measured as the size of the observed stained pitch in the pitch size measurement step, the pitch content calculation step can calculate the content (or content percentage (%)) according to the average value of the equivalent circle diameter of the pitch in the pulp slurry. For example, the pitch content can be calculated by size, such as, "In the pulp slurry, the content (%) of pitch with an average equivalent circle diameter of 150 μm or more is 30%, and the content (%) of pitch with an average equivalent circle diameter of less than 150 μm is 70%."

[0045] [System for measuring pitch size in pulp slurry and calculating pitch content] Furthermore, a system for measuring the pitch size in a pulp slurry is also an embodiment of the present invention. Thus, another embodiment of the present invention is a system including a 3D observation image acquisition unit that observes a pulp slurry containing stained pitch in a three-dimensional direction and acquires a 3D observation image of the pulp slurry, and a pitch size measurement unit that analyzes the 3D observation image using image analysis software and measures the size of the observed stained pitch. Furthermore, a system for calculating the pitch content in a pulp slurry is also an embodiment of the present invention. Thus, in addition to the system for measuring the pitch size described above, a system for calculating the pitch content also includes a pitch content calculation unit that calculates the pitch content in the pulp slurry from the size of the dyed pitch measured by the pitch size measuring unit, which is also an embodiment of the present invention.

[0046] Furthermore, although not essential components, the pitch size measurement system and pitch content calculation system of the present invention may include one or more of the following: a 3D observation image acquisition unit, a pitch dyeing agent addition unit, a pulp fiber dyeing agent addition unit, a drug addition amount determination unit, an output unit, and a drug addition unit.

[0047] Figure 4 is a schematic diagram of the pitch content calculation system according to the present invention. This pitch content calculation system 1 comprises a 3D observation image acquisition device 2 for capturing a 3D observation image of a pulp slurry, a calculation device 3, and an output device 4. The output device 4 may be integrated with the calculation device 3 or provided separately.

[0048] Of the above, the calculation unit 3 controls the information processing for calculating the pitch content in the pitch content calculation system 1. Figure 5 is a block diagram showing the overall configuration of the apparatus according to the present invention. As shown in Figure 5, the calculation unit 3 according to this embodiment is a calculation unit for calculating the total pitch content in a pulp slurry, and comprises a 3D observation image acquisition unit 31, a pitch size measurement unit 32 that analyzes the 3D observation image using image analysis software and measures the size of the observed stained pitch, and a pitch content calculation unit 33 that calculates the pitch content in the pulp slurry and the pitch content from the size of the stained pitch. Although these parts are described here as being contained within a single apparatus, each part may be contained in a separate apparatus, or each part may be contained in multiple apparatuses. Furthermore, the output device is an example of an output unit, and the 3D observation image acquisition device 2 is an example of a 3D observation image acquisition unit, but they will not be particularly distinguished in the following description.

[0049] (3D observation image acquisition unit) This method captures three-dimensional observation images of a pulp slurry containing stained pitch, and can be performed using known means such as microscopes and fluorescence microscopes.

[0050] (3D image acquisition unit) The 3D image acquisition unit 31 acquires a 3D observation image of the pulp slurry including the staining pitch, and the acquisition of the 3D observation image can be carried out in the same manner as the 3D observation image acquisition step in the method invention described above.

[0051] (Pitch size measurement unit) The pitch size measuring unit 32 measures the size of the observed staining pitch, and the measurement of the size of the observed staining pitch can be carried out in the same manner as the pitch size measuring step in the method invention described above.

[0052] (Pitch content calculation unit) The pitch content calculation unit 33 calculates the pitch content in the pulp slurry from the measured size of the dyed pitch, and the calculation of the pitch content can be carried out in the same manner as the pitch content calculation step in the method invention described above.

[0053] (Output section) The output unit 4 is configured to output at least the pitch content in the pulp slurry calculated by the pitch content calculation unit 33. The output unit 4 may, for example, display the pitch content in the pulp slurry over time. The output unit 4 may also output a warning, for example, when the pitch content in the pulp slurry exceeds a certain threshold.

[0054] [Programs for measuring pitch size, programs for calculating pitch content] Furthermore, a program for measuring the pitch size in a pulp slurry is also an embodiment of the present invention. Thus, a program in which a computer functions as a 3D observation image acquisition unit and a pitch size measurement unit, wherein the 3D observation image acquisition unit acquires a 3D observation image of the pulp slurry obtained by observing the pulp slurry including the stained pitch in a 3D direction, and the pitch size measurement unit analyzes the 3D observation image using image analysis software to measure the size of the observed stained pitch is also an embodiment of the present invention. Furthermore, a program for calculating the pitch content in a pulp slurry is also an embodiment of the present invention. Therefore, in addition to the program for measuring the pitch size in the pulp slurry, a computer is further configured to function as a pitch content calculation unit, and the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the dyed pitch measured by the pitch size measurement unit. Furthermore, the 3D observation image acquisition unit, pitch size measurement unit, and pitch content calculation unit can be the same as those described above in terms of method and system, so their explanation is omitted here.

[0055] [Devices for measuring pitch size, devices for calculating pitch content] Furthermore, a device for measuring the pitch size in a pulp slurry is also an embodiment of the present invention. Thus, a device comprising a 3D observation image acquisition unit and a pitch size measurement unit, wherein the 3D observation image acquisition unit acquires a 3D observation image of the pulp slurry obtained by observing the pulp slurry including the stained pitch in a 3D direction, and the pitch size measurement unit analyzes the 3D observation image using image analysis software to measure the size of the observed stained pitch is also an embodiment of the present invention. Furthermore, an apparatus for calculating the pitch content in a pulp slurry is also an embodiment of the present invention. Thus, an apparatus for measuring the pitch size in the pulp slurry further comprises a pitch content calculation unit, and the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the dyed pitch measured by the pitch size measurement unit is also an embodiment of the present invention. Furthermore, the 3D observation image acquisition unit, pitch size measurement unit, and pitch content calculation unit can be the same as those described above in terms of method and system, so their explanation is omitted here.

[0056] [Method for optimizing the dosage of pitch control agent added to pulp slurry] Furthermore, a method for optimizing the dosage of a pitch control agent, which determines the amount of pitch control agent to be added to a pulp slurry based on the pitch size obtained by the pitch size measurement method of the present invention, or the pitch content obtained by the pitch content calculation method of the present invention, is also an embodiment of the present invention.

[0057] In the pitch control agent dosage optimization method of the present invention, for example, when the equivalent circle diameter of the pitch size obtained by the pitch size measurement method of the present invention exceeds a specific equivalent circle diameter value, the amount of pitch control agent added to the pulp slurry can be increased. This allows for the determination of the dosage of the pitch control agent added to the pulp slurry based on the pitch size obtained by the pitch size measurement method of the present invention. The pitch size used to determine the dosage of the pitch control agent added to the pulp slurry is not limited to the average equivalent circle diameter, but can be based on the pitch size obtained by the pitch size measurement method of the present invention (e.g., radius, equivalent circle diameter, longest diameter, shortest diameter, outer circumference, area, surface area, volume, etc.). Furthermore, the specific value of the pitch size obtained by the pitch size measurement method of the present invention that serves as a criterion for determining the dosage of the pitch control agent added to the pulp slurry can be determined according to the control capability required in the paper and pulp manufacturing process.

[0058] Furthermore, the method for optimizing the amount of pitch control agent according to the present invention allows for determining the amount of pitch control agent added to the pulp slurry based on the pitch content obtained by the method for calculating the pitch content according to the present invention. For example, if the pitch content obtained by the method for calculating the pitch content according to the present invention exceeds a certain pitch content, the amount of pitch control agent added to the pulp slurry can be increased. In addition, the specific value of the pitch content obtained by the method for calculating the pitch content according to the present invention that serves as a criterion for determining the amount of pitch control agent added to the pulp slurry can be determined according to the control capacity required in the paper and pulp manufacturing process.

[0059] Furthermore, the method for optimizing the dosage of the pitch control agent according to the present invention may involve determining the dosage of the pitch control agent added to the pulp slurry based on information obtained from the pitch size measurement method and the pitch content calculation method according to the present invention.

[0060] In the pitch control agent dosage optimization method of the present invention, information obtained by the pitch size measurement method and pitch content calculation method of the present invention can be used to create and utilize pitch control agent addition information, such as a function showing the relationship between the pitch size in the pulp slurry and the amount of pitch control agent added, a lookup table, or a trained model showing the relationship between the pitch content in the pulp slurry and the amount of agent added, or a function showing the relationship between the pitch content in the pulp slurry and the amount of pitch control agent added, a lookup table, or a trained model showing the relationship between the pitch content in the pulp slurry and the amount of agent added. The pitch control agent addition information can be used in combination with the above information showing the relationship between the pitch information (pitch size, pitch content) in the pulp slurry and the amount of pitch control agent added.

[0061] The pitch control agent used in the above-described method for optimizing the dosage of the pitch control agent is not particularly limited as long as it can prevent the formation of the target pitch, and examples include surfactants, polymers, inorganic materials, organic compounds, oils, starches, proteins, enzymes, cyclodextrins, water-soluble cellulose, emulsifiers, oxidizing agents, and chelating agents. [Examples]

[0062] The embodiments of the present invention will be described in more detail below, but the present invention is not limited to the following examples.

[0063] [Test Example 1] Pitch Size Measurement Test (Example 1) A pulp slurry sample was obtained by adding 1 μL of a 30% diluted hydrophobic dye to a recycled paper pulp slurry (200 μL) mainly composed of ethylene vinyl acetate copolymer as the pitch component. A pulp slurry sample with controlled fluidity was prepared by adding agar solution to the obtained sample. Next, the obtained pulp slurry sample was examined using an optical fluorescence microscope (Olympus APX100) at a size of 2.4 × 3.5 mm. 2Observations were made within this range, and 3D observation images were acquired. The obtained 3D observation images were analyzed using image analysis software (WinROOF) attached to the optical microscope, and the pitch size was measured using the indicators shown in Table 1 below. The results obtained are shown in Table 1. The images observed using a fluorescence microscope are shown in Figure 6.

[0064] (Comparative Example 1) A pulp slurry sample was obtained by adding 1 μL of a 30% diluted hydrophobic dye to a recycled paper pulp slurry (200 μL) mainly composed of ethylene vinyl acetate copolymer as the pitch component. Next, the obtained pulp slurry sample was cut to 1.6 × 2.2 mm. 2 The pitch size was measured by observing the cell range using a Thermo Fisher automated cell counter (Countess II FL). The results obtained are shown in Table 2. The observed images are shown in Figure 7.

[0065] [Test Example 2] Method for measuring pitch content A recycled paper pulp slurry containing ethylene vinyl acetate copolymer as pitch was dried completely at 105°C, and then subjected to organic solvent extraction (120°C, 40 minutes) to measure the amount of pitch in the pulp slurry. The measurement results showed that the pitch content was 2.5% by weight relative to 100% by weight of solids (i.e., pulp) in the pulp slurry.

[0066] [Table 1]

[0067] [Table 2]

[0068] Comparing Tables 1 and 2 above, it can be seen that even when observing the same pulp slurry within the same observation range, more pitch is observed using the pulp slurry observation method shown in Example 1. In other words, using the pulp slurry observation method shown in Example 1, the pitch component can be observed throughout the entire pulp slurry.

[0069] Based on the results above, it was confirmed that the pulp slurry observation method shown in Example 1 allows for observation of the pitch component throughout the pulp slurry and enables more accurate measurement of the pitch size in the pulp slurry, resulting in a more accurate value for the pitch content calculated from the obtained pitch size. [Explanation of Symbols]

[0070] 1. Pitch Content Calculation System 2. 3D observation and image acquisition device 3 Computing device 31 3D observation image acquisition unit 32 Pitch size measurement section 33 Pitch content calculation unit 4 Output device

Claims

1. A method for measuring the pitch size in a pulp slurry, The steps include adding a pitch staining agent to a pulp slurry to obtain a pulp slurry containing stained pitch, A three-dimensional observation image acquisition step involves observing the pulp slurry containing the aforementioned staining pitch in a three-dimensional direction and obtaining a three-dimensional observation image of the pulp slurry. The pitch size measurement step involves analyzing the aforementioned three-dimensional observation image using image analysis software and measuring the size of the observed staining pitch. A pitch size measurement method including the following.

2. The aforementioned three-dimensional observation image acquisition step involves acquiring a three-dimensional observation image of a pulp slurry containing stained pitch and pulp fibers. The pitch size measurement method according to claim 1, wherein the image analysis in the pitch size measurement step includes removing the image of pulp fibers from the three-dimensional observation image.

3. The pitch size measurement method according to claim 1 or 2, wherein the pitch staining agent is a fluorescent staining agent, and the three-dimensional observation image acquisition step involves sequentially changing the fluorescence detection wavelength to capture a planar image of the pulp slurry obtained from a fluorescence microscope at each detection wavelength, and generating a three-dimensional observation image based on the planar image to acquire a three-dimensional observation image of the pulp slurry.

4. A method for calculating pitch content, comprising a pitch content calculation step of calculating the pitch content in a pulp slurry from the size of the stained pitch obtained by the pitch size measurement method according to claim 1 or 2.

5. A three-dimensional observation image acquisition unit performs observation of the pulp slurry including the stained pitch in a three-dimensional direction and acquires a three-dimensional observation image of the pulp slurry. A system including a pitch size measurement unit that performs image analysis on the aforementioned three-dimensional observation image using image analysis software and measures the size of the observed staining pitch.

6. The system according to claim 5, further comprising a pitch content calculation unit that calculates the pitch content in the pulp slurry from the size of the dyed pitch measured by the pitch size measurement unit.

7. The computer is used as a 3D observation image acquisition unit and a pitch size measurement unit. The three-dimensional observation image acquisition unit acquires a three-dimensional observation image of the pulp slurry obtained by observing the pulp slurry including the staining pitch in a three-dimensional direction. The pitch size measurement unit is a program that analyzes the three-dimensional observation image using image analysis software and measures the size of the observed staining pitch.

8. The computer is further configured to function as a pitch content calculation unit. The program according to claim 7, wherein the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the dyed pitch measured by the pitch size measurement unit.

9. It is equipped with a 3D observation image acquisition unit and a pitch size measurement unit, The three-dimensional observation image acquisition unit acquires a three-dimensional observation image of the pulp slurry obtained by observing the pulp slurry including the staining pitch in a three-dimensional direction. The pitch size measurement unit is a device that analyzes the three-dimensional observation image using image analysis software and measures the size of the observed staining pitch.

10. Furthermore, it is equipped with a pitch content calculation unit, The apparatus according to claim 9, wherein the pitch content calculation unit calculates the pitch content in the pulp slurry from the size of the stained pitch measured by the pitch size measurement unit.

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