JP2016075573A - Determination method of fibrillated state of vegetable fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination method of a fibrillated state of a vegetable fiber capable of estimating a fibrillated degree of a vegetable fiber such as a hemp with a simple structure and without requiring a long time.SOLUTION: The determination method includes: (A) a step of acquiring a plot or a calibration curve of a fibrillated state and an increased portion due to water absorption by immersing a vegetable fiber into water for a predetermined time after measuring a mass of vegetable fiber for each of a plurality of vegetable fibers known in fibrillated state showing a degree of fibrillation, then applying pressure thereto to extract water therefrom, and then calculating the increased portion due to water absorption on the basis of a ratio of the mass after extracting water to the mass before immersed into water or a difference thereof; (B) a step of calculating the increased portion due to water absorption on the basis of the ratio of the mass after extracting water to the mass before immersed into water or the difference thereof, for a vegetable fiber unknown in fibrillated state; and (C) a step of collating the increased portion due to water absorption relating to the unknown vegetable fiber of the step (B) with the plot or the calibration curve acquired in the step (A) and determining the fibrillated state of the vegetable fiber unknown in fibrillated state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for determining the defibrated state of plant fibers.

  Hemp such as jute and kenaf is used as a raw material for fiber boards by defibrating fiber bundles obtained from the bast portion (Patent Document 1).

  When manufacturing a fiber board, the fiber bundle is defibrated to form a non-woven fiber mat. Then, an adhesive resin is supplied during or after the fiber mat is formed, and the fiber mat supplied with this resin is hot-pressure formed.

  Fibreboard is stronger than wood boards such as particle boards (PB) and MDF (medium density fiberboard) used for housing, interior, and construction materials, and is dry when absorbing water or absorbing moisture. Small dimensional change with time. Therefore, when used for flooring, gaps and push-ups are suppressed, and when used for walling, warping of the wall due to dimensional changes after construction can be suppressed because of high strength and moisture permeability. Moreover, when it uses as a base material of interior members, such as a door and a door material, intensity | strength is high and the curvature and deviation resulting from a dimensional change are also suppressed.

  Hemp fiber as a raw material for fiber boards separates fiber bundles by passing the fiber bundles through a defibrating device that has a mechanism in which a cylinder with sharp pins and cutting blades rotates at high speed. It is obtained by doing.

  The defibrated state of hemp fibers varies depending on the processing conditions of such a defibrating device, variations in fiber bundles to be processed, etc., and this defibrated state affects the above-described physical properties of the fiber board to be manufactured. Therefore, there has been a demand for a method capable of grasping the degree of fiber defibration in comparison with a known defibration state and evaluating based on the degree.

  Conventionally, as a method of evaluating the defibration state of fibers, a fiber reinforced composite material in which aramid fibers are mixed in cellulose or powder is used as a sample, and these are observed and measured with a microscope, and an analytical method based thereon is used. Have been proposed (Patent Documents 2 and 3).

Japanese Patent No. 4085861 JP 2013-186034 A Japanese Patent Laid-Open No. 2000-055904

  However, a method for simply evaluating the defibrated state when defibrating hemp fibers has not been proposed. An analytical method such as surface area or true specific gravity can be used to evaluate the defibrated state, but there are problems such as cost constraints and long time required for measurement in the equipment configuration for evaluation. It was.

  The present invention has been made in view of the circumstances as described above, and is a plant capable of evaluating the degree of fibrillation of plant fibers such as hemp with a simple configuration and without requiring a long time. It is an object to provide a method for determining the defibration state of a fiber.

In order to solve the above problems, the method for determining the defibrated state of a plant fiber of the present invention is characterized by including the following steps (A), (B), and (C):
(A) After measuring the mass of a plant fiber for each of a plurality of plant fibers having a known defibration state indicating the degree of defibration, the plant fiber is immersed in water for a predetermined time, and water in which the plant fiber is immersed After squeezing water by applying a predetermined pressure to the water, the mass of the plant fiber is measured, based on the ratio or difference between the mass of the plant fiber after squeezing the water and the mass of the plant fiber before immersing in water Calculating an increase due to water absorption and obtaining a plot or calibration curve of the defibrated state and the increase due to water absorption;
(B) Based on the ratio or difference between the mass of the plant fiber after squeezing water and the mass of the plant fiber before immersing in water under the same conditions as in the step (A) for the plant fiber whose defibration state is unknown A step of calculating the increase due to water absorption; and (C) the plot or calibration curve obtained in step (A) for the increase due to water absorption for the plant fiber whose fibrillation state is unknown calculated in step (B). The process of collating and determining the defibration state in the plant fiber whose defibration state is unknown.

  According to the present invention, the degree of fibrillation of plant fibers such as hemp can be evaluated with a simple configuration and without requiring a long time.

It is the figure which showed roughly the apparatus structure of the Example. The result of plotting the relationship between the defibrated state and water absorption at an immersion time of 1 minute and N = 2 is shown. The result of having plotted the relationship between the defibrated state and water absorption in each of immersion time 1 minute and 24 hours is shown.

  Hereinafter, embodiments of the present invention will be described.

The method for determining the defibrated state of the plant fiber of the present embodiment includes the steps (A), (B), and (C).
<Process (A)>
In this step (A), a plot or calibration curve of the defibrated state and the increase due to water absorption of the plant fiber for collating with a plant fiber whose defibrated state is unknown, which is a target for evaluating the degree of defibration. obtain.

  First, a plurality of plant fibers whose defibration state indicating the degree of defibration is known is prepared. As this plant fiber, the same type as the plant fiber whose defibration state is unknown, which is a target for determining the defibration state, is used.

  These plant fibers have different defibrating states from each other, and for example, those in which the number of times of defibration by the defibrating apparatus is changed are used.

  Here, defibration can be performed as follows, for example. First, a fiber bundle having a length of several tens of centimeters to several meters and a width of 5 to 30 mm is collected and weighed from a plant as a raw material of the fibers. Next, the fiber bundle is put into a cutting machine such as a rotary cutter and cut to have a length of about 5 to 10 cm.

  Then, the cut fiber bundle is defibrated by a defibrating device such as a lapping machine. A defibrating device is a machine that has a mechanism in which a cylinder with a pin with a sharp tip and a cutting blade rotates at high speed. By passing the fiber bundle through this, the fiber bundle is separated, defibrated, and fiberized. Can do.

  For example, it can be fibrillated and fiberized into an aggregate of fibers having an average fiber length of about 5 to 200 mm and an average fiber diameter of several tens to several hundreds of μm. The average fiber length and average fiber diameter vary depending on the conditions of the defibrating device and the number of defibrating. In one example, the fiber is defibrated until the average fiber length is 5 to 100 mm and the average fiber diameter is 70 to 400 μm. Alternatively, fine fibers having an average fiber diameter of 20 to 70 μm and an average fiber length of 5 to 100 mm in which a fuzzy structure is formed by changing the defibrating conditions such as increasing the number of defibrating treatments performed by the defibrating apparatus. can get.

  Here, the average fiber length is measured using a fiber length distribution measuring machine or the like. The average fiber diameter is measured as an average value obtained by measuring fiber diameters at a plurality of locations from images of an optical microscope or an electron microscope.

  For example, when plant fibers are used for fiber boards, if the average fiber length and average fiber diameter are within the above ranges, the density of the fiber boards should be in an appropriate range, and the strength and dimensional stability due to fiber entanglement It is suitable for obtaining the effect of crystallization effectively.

  Next, the mass of the plant fiber is measured for the plant fiber whose defibrated state is known. The mass of the plant fiber can be measured with a normal measuring instrument. If there are any contaminants such as resin powder, remove them thoroughly by shaking.

  Although the mass of the plant fiber to be used is not particularly limited, it is preferably 5 to 50 g in consideration of evaluation accuracy and simplicity.

  Next, the plant fiber whose mass has been measured is immersed in water for a predetermined time. As a result, water is sufficiently permeated into the plant fiber to absorb water.

  It is desirable that the amount of water immersed in the plant fiber is always constant from the viewpoint of reducing the error as much as possible by determining the protocol, but it is not necessarily constant, and the entire plant fiber is immersed. It may be more than the amount that can be.

  When the plant fiber is immersed in water, a container that can store the plant fiber and water is used. The container is not particularly limited in its shape and capacity as long as it can squeeze out water by applying a predetermined pressure. Good. In addition, it is preferable that the top can be closed by a lid that can suppress water transpiration and dust intrusion during immersion.

  In addition, a small hole for draining water is provided on the bottom and side surfaces of the container so that the plant fiber can be immersed in water for a predetermined time and then squeezed out by applying a predetermined pressure. It is preferable. Alternatively, a large opening may be provided at the bottom of the container, and a plate having a large number of small holes for draining water may be separately disposed on the bottom surface. If such a plate is prepared separately from the container, it is easy to produce holes and to extract plant fibers after squeezing water by applying a predetermined pressure. This plate having a large number of holes can store water squeezed below the bottom of the container so that the water flowing down from the container can be fixed to the upper surface of the tray, and the workability is good. is there.

  The size and number of the holes for draining the water are not particularly limited, but when a predetermined pressure is applied to squeeze out the water, a moderate resistance pressure is applied, and the hole is accommodated in the container. It is considered that the plant fiber does not flow out and that water is quickly discharged out of the container. Therefore, it is preferable that the hole for draining water has a mesh-like porosity. The mesh-shaped porous pore size is, for example, 1 to 5 mm.

  If the container has a transparent side surface, the immersed state of the plant fibers can be easily observed. Therefore, a transparent resin, a transparent glass material, etc. can be used preferably.

  When immersing the plant fiber in water, if necessary, it may be appropriately stirred by manual stirring using a rod-shaped member, stirring using a stirring bar, mechanical stirring using a stirring blade, etc. Immerse in the stationary state as much as possible.

  The time for immersing the plant fiber in water is determined in advance by a protocol. If there is reproducibility, a short time is sufficient, but an appropriate time is set in consideration of the plot of the defibrated state and the increase due to water absorption or the dynamic range and reproducibility of the increase due to water absorption in the calibration curve. The immersion time can be, for example, 0.5 minute to 24 hours, but is preferably 1 to 10 minutes for practical use. Moreover, at the time of immersion, it is desirable that the temperature conditions and the like be as constant as possible in a range of, for example, 10 to 25 ° C. so that the water absorption does not vary.

  Next, water is squeezed out by applying a predetermined pressure to the water in which the plant fiber is immersed. For example, the method of pressing the water accommodated in the container with a hard plate-shaped member from the upper surface is mentioned. The hard plate-like member having a shape slightly smaller than the inner diameter of the container can apply pressure uniformly to the upper surface as a whole. Although the material is not particularly limited, a metal material, a resin material, or the like that can be easily processed can be used.

  This plate-like member is preferably connected to a pressure gauge in order to monitor the pressure on water. For example, a bar-like part is provided vertically from the upper surface of the plate-like member, and the bar-like part is pressed against a sensor part below a small pressure gauge that can be held with one hand. By grasping the pressure gauge and pressing the rod-like portion downward while monitoring the scale, water can be squeezed out from the bottom of the container while applying a certain pressure by the plate-like member.

This pressure is preferably 0.01 to 0.1 N / mm ² considering a sufficient pressure to squeeze out water in the gaps between the fibers.

  Here, the resistance pressure depends on conditions such as the mesh on the bottom surface of the container, but the water is squeezed out by pressing until the water in the gap between the fibers is squeezed out and the water droplets do not spill. Thereby, the precision of evaluation is securable.

  Next, the mass of the vegetable fiber which squeezed water is measured. The mass of the plant fiber can be measured with a normal measuring instrument, but it is carried out moderately and promptly to the extent that water does not evaporate. This mass is good also as a difference with the empty container mass measured beforehand, measuring the mass of the container beforehand, measuring the mass of the container with the fiber after squeezing out. In addition, when a large opening is provided in the bottom of the container as described above, and a plate having a large number of small holes for draining water is disposed on the bottom, the container is lifted from the plate and then formed into a plate shape. The remaining plant fiber may be taken out and measured.

  Next, based on the ratio or difference between the mass of the plant fiber after squeezing water and the mass of the plant fiber before immersing in water, an increase due to water absorption is calculated. As defibration progresses, the surface area of the fiber increases, resulting in an increase in surface water absorption. The profile of the increase due to water absorption and the defibrated state reflects this. Examples of the increase due to water absorption include the rate of mass increase relative to the unit fiber mass and other values obtained by converting the difference between the mass after water absorption and the mass before water absorption into the unit fiber mass. The wide method is preferable.

Next, a plot or calibration curve of the defibrated state and the increase due to water absorption is obtained. As for the defibrated state, when the defibrated material is passed through the defibrating machine and the measurement is performed once to several times, the defibrated state may be plotted side by side in ascending order of the number of defibrated times. The calibration curve of this plot can be created by fitting by regression analysis such as the least square method.
<Process (B)>
Next, based on the ratio or difference between the mass of the plant fiber after squeezing water and the mass of the plant fiber before immersing in water under the same conditions as in the step (A) for the plant fiber whose defibration state is unknown To calculate the increase due to water absorption.

  First, a sample of plant fiber whose defibration state is unknown is collected. For example, it can be taken out from a fiber board production line in a timely manner. If there are any contaminants such as resin powder, remove them thoroughly by shaking.

  The amount of plant fiber used here is not particularly limited, but it is preferable to align it with the step (A) in consideration of evaluation accuracy and simplicity.

And the mass of a vegetable fiber is measured. Thereafter, under the same conditions as in the step (A), the plant fiber is immersed in water for a predetermined time, and a predetermined pressure is applied to the water in which the plant fiber is immersed to squeeze out the water, and then the mass of the plant fiber is measured. Then, based on the ratio or difference between the mass of the plant fiber after squeezing out the water and the mass of the plant fiber before being immersed in water, an increase due to water absorption is calculated.
<Process (C)>
Next, the increase due to water absorption of the plant fiber whose defibration state is unknown calculated in the step (B) is collated with the plot or calibration curve obtained in the step (A), and the plant fiber whose defibration state is unknown Determine the defibrated state. Specifically, when the vertical axis represents the increase due to water absorption and the horizontal axis represents the defibrated state, the horizontal axis corresponding to the increase due to water absorption represents the defibrated state value and the defibrated state Determine the defibrated state of unknown plant fiber.

  The plant fiber can be evaluated from the defibrated state thus determined. This evaluation result can be used, for example, for management of physical properties of the fiber board. In addition, an appropriate threshold value can be set for the defibrated state on the horizontal axis, such as whether it is within a predetermined standard range, accompanying the determination.

  In the present embodiment, for example, plant fibers such as hemp-based natural fibers, palm fibers, agricultural waste fibers, and wood fibers can be used as the plant fibers.

  Hemp-based natural fibers are fibers made from bast fiber-based plants such as kenaf, jute, flax, ramie, hemp, and sisal. Bast fiber-based plants are already distributed as general industrial raw materials in the spinning and nonwoven fabric industries, and can be stably procured. A fiber having high strength and good dimensional stability can be obtained by mechanically defibrating the fiber bundle obtained from the bast portion of the bast fiber plant. Moreover, by appropriately setting the defibrating conditions, the fiber bundle can be defibrated to a predetermined fiber length and fiber diameter, and the target fiber can be obtained relatively easily.

  Palm fiber is fiber made from plants such as oil palm and coconut palm. This plant material can also be procured stably. High strength by defibrating the fiber part after squeezing palm oil from the fruit bunches such as oil palm and coconut to the prescribed fiber length and fiber diameter, similar to the bast fiber bundle described above Can be obtained easily.

  Agricultural waste fiber is a fiber made from agricultural waste such as sugar cane, corn, bamboo, and rice. For example, a bagasse fiber having a small bulk density can be obtained by drying a squeezed residue (hereinafter referred to as bagasse) after boiling sugar from sugarcane and then processing it into a fiber. Then, similarly to the bast fiber bundle described above, the target fiber can be easily obtained by defibrating to a predetermined fiber length and fiber diameter. Bagasse has conventionally been discarded or used as boiler fuel, paper raw materials, livestock feed, fertilizer, and the like, but has recently attracted attention as an available biomass resource due to increasing environmental problems.

  In addition to bagasse, the desired agricultural waste fibers can be obtained by defibrating corn, bamboo stalks, rice straw and other raw materials. By using raw materials that have been discarded in the past, waste can be reduced and valuable resources can be saved. In addition, the cost of the fiber board can be reduced.

  Wood fiber is a fiber made from conifers, hardwoods, and the like. The wood fiber can use miscellaneous trees, woodwork scraps, waste materials, defective timbers, thinned wood, etc., which are generally used as MDF raw materials. For this reason, it is possible to effectively use wood-based raw materials that are valuable resources from the viewpoint of the global environment. Similar to the bast fiber bundle described above, the intended fiber can be easily obtained by defibrating such a wood-based material to a predetermined fiber length and fiber diameter.

  Moreover, the fiber obtained by defibrating the Dongoros bag currently distributed in large quantities as a transportation bag, such as a grain, to a predetermined fiber diameter can also be used. Dongoross bags are made of hemp natural fibers such as jute. For this reason, there is an advantage that the raw fiber can be stably procured in addition to the advantage that the hemp-based natural fiber having excellent strength characteristics can be obtained by opening the dongoros bag. Furthermore, since the used Dongoross bag can be purchased at a low price, it is possible to obtain a fiber board that is cheaper and has good strength, dimensional stability, and moisture permeability.

  Determination of the defibrated state of the plant fiber by the method of the present embodiment is suitable for quality control and the like when manufacturing the fiber board.

  When manufacturing a fiber board using this plant fiber, first, a resin is supplied to a fiber board that has been defibrated and made into a nonwoven fabric. The method for supplying the resin is not particularly limited. For example, a wet method in which a nonwoven fabric is impregnated with a water-soluble resin, a dry method in which resin fibers or resin powders are mixed during molding of the nonwoven fabric, and the like can be used. .

  Examples of the resin include those containing a thermosetting resin such as urea resin, phenol resin, melamine resin, epoxy resin, urethane resin, and unsaturated polyester resin as a resin component. Moreover, what contains thermoplastic resins, such as a polypropylene resin, a polyethylene resin, a polyethylene terephthalate (PET) resin, a vinyl chloride (PVC) resin, as a resin component can also be mentioned.

  Next, the obtained mixture is formed into a mat to form a fiber mat. For making the mixture into a fiber mat, for example, an apparatus called a mat former that continuously produces fiber mats can be used. The fiber mat can also be formed by a method such as spraying a mixture on a mold. In the dry method in which the resin powder is mixed with cotton, next, if necessary, a mat heat treatment for heating the fiber mat is performed to melt the granular adhesive in the fiber mat.

  Next, a fiber mat is obtained by hot pressing the fiber mat into a plate shape. For hot pressing of the fiber mat, for example, a continuous press device that conveys the fiber mat while applying pressure to a gap between a pair of heated steel belts, or pressurizing the fiber mat between a plurality of heated hot plates. A multi-stage press apparatus etc. can be used. The molding conditions are not particularly limited, but a molding temperature of 120 to 190 ° C. and a molding pressure of 1 to 4 MPa are preferable. What is necessary is just to set a shaping | molding time suitably according to the board thickness and shaping | molding temperature of a fiber board.

  Next, post-processing such as adjusting the moisture content (curing) or cutting into a predetermined size is performed on the fiber board obtained after molding, as necessary.

  The fiber board manufactured in this way is effectively bonded with an adhesive in a state where the fibers are intertwined with each other, and has good strength, dimensional stability, and moisture permeability.

  Such a fiber board can be used as a building member such as a flooring material, a wall material, a ceiling material, and a field board. Moreover, it can also utilize as a base material of interior members, such as a door and a door material.

  And, by applying the method for determining the fibrillation state of the plant fiber according to the above-mentioned steps (A), (B), (C), after defibration, after the formation of the fiber mat, etc. In an appropriate step, the defibrated state can be evaluated.

  According to this embodiment described above, the degree of fibrillation of plant fibers such as hemp can be evaluated with a simple configuration and without requiring a long time.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

  As a plant fiber, a jute bast fiber bundle (width: 1-2 cm, length: 2-4 m) was cut in the length direction by a cutting machine, and then the jute was mechanically defibrated using a lapping machine Fiber was used.

  Fiber samples were prepared in which the number of times of defibrating treatment with a lapping machine was 0 (undefibrated), 2, 4 or 6 times.

  The defibrated state was identified as the number of defibrations. The average fiber length of the undefibrated fiber is about 10 mm, and the average fiber length and the average fiber diameter are gradually reduced by increasing the number of times applied to the lapping machine and increasing the degree of defibration.

  As shown in FIGS. 1A and 1B, a container 1, a tray 2, a holding plate 5, and a pressure gauge 6 were prepared.

  The container 1 is made of a transparent resin having a diameter of 110 mm, and has a large hole at the bottom for draining water.

  The tray 2 has a metal 3 mm mesh perforated plate 3 attached to the upper surface opening, and can receive water from the bottom of the container 1.

  The pressure plate 5 is a disk-shaped plate member made of metal and having a diameter of 95 mm, and is a small pressure gauge 6 that can be gripped by hand and has a display unit via a metal bar 5a attached to the upper surface perpendicular to the disk. By pressing the metal bar 5a against the sensor portion 6a at the lower part of the water, the pressure on the holding plate 5 pressed against the upper surface of water can be detected.

  A resin sheet 4 that does not transmit water is sandwiched between the bottom of the container 1 and the perforated plate 3, the container 1 is placed on the perforated plate 3, 40g of jute fiber 10 is put therein, and 1L of water is further added. Soaked. The immersion time was set to two types of 1 minute and 24 hours, and the upper surface was closed by covering the container 1 during the immersion.

Thereafter, the lid is removed, the resin sheet 4 is taken out from between the bottom of the container 1 and the porous plate 3, and the presser plate 5 is lowered by the pressure gauge 6 through the metal rod 5a as shown in FIG. Then, the pressure was lowered at a constant pressure of 100 N (0.014 N / mm ² ) to squeeze out water, and dehydrated through the perforated plate 3.

The dehydrated jute fiber was weighed with a measuring instrument. About the sample of each jute fiber, the water absorption rate was calculated from the mass of the jute fiber after squeezing (water absorption mass) and the mass of the jute fiber before being immersed in water (fiber mass) as an increase due to water absorption from the following equation. .
Water absorption rate = (water absorption mass) / (fiber mass)
A plot of defibrated state and water absorption was made. FIG. 2 shows the result of plotting the relationship between the defibration state (number of defibration) and the water absorption rate when the immersion time is 1 minute and N = 2.

  It was recognized that the water absorption rate tends to increase as the number of defibration increases from undefibrated, twice defibrated, four times defibrated, six times defibrated. The water absorption rate changed from 5.2 to 6.7 from undefibrated to 6th defibrated, and was reproducible. From this result, the mass of jute fiber (water absorption mass) after squeezing jute fiber whose defibration state is unknown under the same conditions as above and the mass (fiber mass) of jute fiber before being immersed in water are measured. It was revealed that the defibration state can be determined by calculating the water absorption rate and comparing it with this plot.

  FIG. 3 shows the results of plotting the relationship between the defibrated state (number of defibration) and the water absorption rate at the immersion time of 1 minute and 24 hours, respectively.

  It is recognized that the water absorption rate tends to increase as the number of times of defibration increases from undefibrated to 2nd defibrated, 4th defibrated, and 6th defibrated at both immersion times of 1 minute and 24 hours. It was. As for the water absorption rate, the results differed between the immersion time of 1 minute and 24 hours, and the water absorption rate as a whole was higher at the immersion time of 24 hours than in the case of the immersion time of 1 minute, and the dynamic range was widened.

  From this result, the mass of jute fiber (water absorption mass) after squeezing jute fiber whose defibration state is unknown under the same conditions as above and the mass (fiber mass) of jute fiber before being immersed in water are measured. It was revealed that the defibration state can be determined by calculating the water absorption rate and comparing it with this plot. Although the results differ depending on the dipping time, when the number of times of fibrillation increases, a certain tendency that the water absorption rate tends to increase is recognized, and reproducibility and variation are at a level where the number of times of fibrillation can be distinguished. From this, it was suggested that the defibration state can be accurately determined by verifying the optimum conditions of the immersion time and the pressure of squeezing, and the sample can be evaluated based thereon.

Claims (3)

A method for determining the defibrated state of a plant fiber, comprising the following steps (A), (B), (C):
(A) After measuring the mass of the plant fiber for each of the plurality of plant fibers of which the defibrated state indicating the degree of defibration is known, the plant fiber is immersed in water for a predetermined time. After squeezing out the water by applying a predetermined pressure to the immersed water, the mass of the plant fiber is measured, and the mass of the plant fiber after squeezing out the water and the plant fiber before being immersed in the water Calculating an increase due to water absorption based on a ratio or difference from the mass of the water, and obtaining a plot or calibration curve of the defibrated state and the increase due to water absorption;
(B) About the plant fiber whose defibration state is unknown, the mass of the plant fiber after squeezing the water and the mass of the plant fiber before being immersed in the water under the same conditions as in the step (A) A step of calculating an increase due to the water absorption based on the ratio or difference to the above; and (C) an increase due to the water absorption for the plant fiber whose defibration state calculated in the step (B) is unknown. The step of collating with the plot or the calibration curve obtained in the step (A) to determine the defibrated state in the plant fiber whose defibrated state is unknown.   The method for determining the defibrated state of a plant fiber according to claim 1, wherein the predetermined time for immersing the plant fiber in the water is 0.5 minutes to 24 hours. The predetermined pressure applied to the water soaked the plant fibers, the method for determining the fibrillation state of the plant fiber according to claim 1 or 2, characterized in that a 0.01~0.1N / mm ² .

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