Manufacturing method of cellulose nanofiber and manufacturing apparatus of cellulose nanofiber

Abstract

To provide a manufacturing method of cellulose nanofibers and a manufacturing apparatus of cellulose nanofibers for enhancing beating efficiency.SOLUTION: A manufacturing method of cellulose nanofibers includes: fibrillating a raw material including wood fibers; after fibrillating, classifying the fibrillated raw material to long fibers and short fibers by using a fiber classifier; and beating the classified raw material including the short fibers by using a refiner 3 to manufacture cellulose nanofibers.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cellulose nanofiber production method and a cellulose nanofiber production apparatus, and in particular to a cellulose nanofiber production method and a cellulose nanofiber production apparatus that can improve beating efficiency. [Background technology]

[0002] In a conventional method for producing cellulose nanofibrils, the pulp is beaten in a refiner (22), the beaten raw material is stored in a CNF storage tank (30), the raw material from the CNF storage tank (30) is processed by a device (34) capable of filtering out pulp with a relatively low CNF level and longer fibers, and the raw material that cannot be processed is connected to and returned to a refiner feed chest for reprocessing by (46) (see patent document). CNF stands for cellulose nanofiber. The numbers in parentheses correspond to the numbers in FIG. 3 described in JP2018-517863A. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-517863 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned method for producing cellulose nanofibrils, as the number of circulations increases (the fiber length becomes shorter), the beating efficiency decreases, and a considerable number of circulations is required to produce effective CNF. In addition, some fibers often remained unbeaten even after repeated circulation, which caused problems such as the purity of the produced CNF not being maintained.

[0005] The present invention provides a cellulose nanofiber production method and a cellulose nanofiber production apparatus that have been devised in consideration of the above problems. [Means for solving the problem]

[0006] The method for producing cellulose nanofibers described in claim 1 involves classifying a raw material containing wood fibers into long fibers and short fibers using a fiber classifier, and then beating the raw material containing the classified short fibers in a refiner to produce cellulose nanofibers.

[0007] In addition, the method for producing cellulose nanofibers described in claim 2 involves defibrating a raw material containing wood fibers, classifying the defibrated raw material into long fibers and short fibers using a fiber classifier, and beating the raw material containing the classified short fibers in a refiner to produce cellulose nanofibers.

[0008] The cellulose nanofiber manufacturing apparatus described in claim 3 includes a fiber classifier that classifies a raw material containing wood fibers into long fibers and short fibers, and a refiner that beats the raw material containing the short fibers classified by the fiber classifier, and produces cellulose nanofibers by beating in the refiner.

[0009] The cellulose nanofiber manufacturing apparatus described in claim 4 comprises a defibrator that defibrates raw material containing wood fibers, a fiber classification device that classifies the raw material defibrated by the defibrator into long fibers and short fibers after defibration, and a refiner that beats the raw material containing the classified short fibers classified by the fiber classification device, and produces cellulose nanofibers by beating in the refiner. Effect of the Invention

[0010] Conventionally, many of the fibers that remain unbeaten even after repeated circulation have long fibers that are broken, which is one of the obstacles to improving beating efficiency. According to the method for producing cellulose nanofibers described in claim 1, the raw material is classified in a fiber classifier before being beaten in the refiner, that is, the raw material containing the classified short fibers is beaten in the refiner, so that the long fibers are removed in advance, the proportion of short fibers is increased, and beating efficiency can be improved.

[0011] Conventionally, many of the fibers that remain unbeaten even after repeated circulation have long fibers that are broken, which is one of the obstacles to improving beating efficiency. According to the method for producing cellulose nanofibers described in claim 2, the raw material containing wood fibers is defibrated at a stage before being beaten in the refiner, and after defibration, the defibrated raw material is classified in a fiber classifier, and the classified raw material containing short fibers is beaten in the refiner, so that the long fibers are removed in advance, the proportion of short fibers is increased, and beating efficiency can be improved.

[0012] Conventionally, many of the fibers that remain unbeaten even after repeated circulation have long fibers that are broken, which is one of the obstacles to improving beating efficiency. According to the cellulose nanofiber production device described in claim 3, the raw material containing the classified short fibers is beaten in the refiner at a stage before it is beaten in the refiner, that is, the long fibers are removed in advance, increasing the proportion of short fibers and improving beating efficiency.

[0013] Conventionally, many of the fibers that remain unbeaten even after repeated circulation have long fibers that are broken, which is one of the obstacles to improving beating efficiency. According to the method for producing cellulose nanofibers described in claim 4, the raw material containing wood fibers is defibrated at a stage before being beaten in the refiner, and after defibration, the defibrated raw material is classified in a fiber classifier, and the classified raw material containing short fibers is beaten in the refiner, so that the long fibers are removed in advance, the proportion of short fibers is increased, and beating efficiency can be improved. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a cellulose nanofiber production apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of a cellulose nanofiber production apparatus according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A cellulose nanofiber manufacturing method and cellulose nanofiber manufacturing apparatus according to one embodiment of the present invention will be described with reference to Figure 1. Cellulose nanofibers are made by finely defibrating cellulose, the main component of plant fibers such as wood, to nano sizes (one millionth of a millimeter).

[0016] N shown in Figure 1 is a cellulose nanofiber manufacturing device. The cellulose nanofiber manufacturing device N includes a pulper 1 that defibrates raw materials containing wood fibers, and after defibration, the raw materials defibrated by the pulper 1 are classified into long fibers and short fibers using a fiber classification device (fractionator) 2. The fiber classification device (fractionator) 2, not shown, has a round hole diameter of 0.25 mm to 0.5 mm or a slit with a slit width of 0.05 mm to 0.1 mm, and performs classification. The fiber is classified using this fiber classification device (fractionator) 2, and then the raw material containing the classified short fibers is refined using a refiner 3. The raw material is refined using the refiner 3 to produce cellulose nanofibers.

[0017] Examples of the raw materials containing wood fibers include kraft pulp (KP), sulfite pulp (SP), GP, TMP, and waste paper pulp. The defibrator 1 is, for example, a pulper. The fiber classification device (fractionator) 2 is, for example, a device that classifies the raw material into short fibers that can pass through a screen and long fibers that cannot, depending on whether the raw material can pass through the screen or not. For example, it is a fractionator manufactured by Valmet Co., Ltd. Short fibres are, for example, fibres having a length of less than 1 mm, and long fibres are, for example, fibres having a length of 1 mm or more. The refiner 3 may be, for example, a peter, a disc refiner, a conical refiner, a grinder, a homogenizer, a supermass collider, or the like.

[0018] Therefore, raw materials containing wood fibers are defibrated to about 2 to 6% (% in the examples of the present invention is by weight) using a defibrator (e.g., a pulper) 1, and then supplied to a fiber classifier (fractionator) 2 with fine holes using a pump 4. In the fiber classification device (fractionator) 2, the long fibers cannot pass through the holes and are returned directly to the defibrator (for example, pulper) 1 via the first return passage 5. In the fiber classification device (fractionator) 2, the short fibers that pass through the holes are concentrated to about 4% in the concentration device 6 and accumulated in the refiner supply tank 7. The CNF is supplied from the refiner supply tank 7 to a refiner (e.g., a conical refiner) 3 by a pump 8, where it is circulated and beaten through a second return passage 9. After being beaten to a predetermined state, it is sent to a finishing tank 11 through a branch passage 10 branching off from the second return passage 9 and becomes finished CNF. The water from the thickening device 6 is returned to the fiberizer (for example, a pulper) 1 through a drainage tank 12, a pump 13, and a third return passage 14.

[0019] That is, conventionally, most of the fibers that remain unbeaten even after repeated circulation are long fibers that are broken into pieces, which is one of the obstacles to increasing the beating efficiency. According to the cellulose nanofiber production apparatus (cellulose nanofiber production method) N of this embodiment, before being beaten in the refiner 3, that is, the raw material containing wood fibers is defibrated in a defibrator 1, and after defibration, the defibrated raw material is classified in a fiber classifying device (fractionator) 2 having, for example, a round hole diameter of 0.25 mm to 0.5 mm or a slit width of 0.05 mm to 0.1 mm, and the raw material containing the classified short fibers is beaten in the refiner 3, so that the long fibers are removed in advance and the proportion of short fibers is increased, thereby improving the beating efficiency.

[0020] If the raw material containing wood fibers is defibrated, and the defibrator 1 can be directly supplied from the pipeline 15, the defibrator 1 can be omitted (see FIG. 2). In FIG. 2, the same parts as those in FIG. 1 are denoted by the same reference numerals, and some of the explanations will be omitted. In such a case, the cellulose nanofiber production apparatus (cellulose nanofiber production method) N shown in Figure 2 classifies a raw material containing wood fibers into long fibers and short fibers using a fiber classifier (fractionator) 2. For example, the fiber classifier (fractionator) 2 has a fiber classifier (fractionator) 2 having, for example, a circular hole diameter of 0.25 mm to 0.5 mm or a slit with a slit width of 0.05 mm to 0.1 mm, and a refiner 3 that beats the raw material containing the short fibers classified by this fiber classifier (fractionator) 2, and cellulose nanofibers can be produced by beating in the refiner 3.

[0021] According to the cellulose nanofiber manufacturing apparatus (cellulose nanofiber manufacturing method) N of this embodiment, the raw material containing the classified short fibers is classified in a fiber classifying device at a stage before it is beaten in the refiner 3, that is, the raw material is beaten in the refiner, so that the long fibers are removed in advance, the proportion of short fibers is increased, and the beating efficiency is improved. Specifically, raw material containing wood fibers is classified using a fiber classifier (fractionator) 2 having a round hole diameter of 0.25 mm to 0.5 mm or a slit with a slit width of 0.05 mm to 0.1 mm, and the classified raw material containing short fibers is beaten in a refiner 3, so that long fibers are removed in advance, the proportion of short fibers is increased, and the beating efficiency is improved. [Explanation of symbols]

[0022] N Cellulose nanofiber manufacturing equipment 1. Fiberizer 2 Fiber classification device (fractionator) 3. Refiner

Claims

1. A raw material containing wood fibers is classified into long fibers and short fibers using a fiber classifier, and the raw material containing the classified short fibers is refined using a refiner to produce cellulose nanofibers. A method for producing cellulose nanofibers, comprising the steps of:

2. A raw material containing wood fibers is defibrated, and after defibration, the defibrated raw material is classified into long fibers and short fibers using a fiber classifier, and the raw material containing the classified short fibers is beaten in a refiner to produce cellulose nanofibers. A method for producing cellulose nanofibers, comprising the steps of:

3. A fiber classifier that classifies a raw material containing wood fibers into long fibers and short fibers; and a refiner that refines the raw material containing the short fibers classified by the fiber classifying device, The cellulose nanofibers are produced by beating them with the refiner. A cellulose nanofiber manufacturing apparatus characterized by the above.

4. A defibrator that defibrates raw materials containing wood fibers; a fiber classifying device that classifies the raw material defibrated by the defibrator into long fibers and short fibers after defibration; and a refiner that refines the raw material containing the short fibers classified by the fiber classifying device, The cellulose nanofibers are produced by beating them with the refiner. A cellulose nanofiber manufacturing apparatus characterized by the above.

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