JP2015052179A - Manufacturing method of woody fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily manufacturing a high-quality woody fiber impervious to chemical modification.SOLUTION: When a woody fiber is prepared by fiberizing a wooden material 1, an admixture of the wooden material and dry ice is obtained by mixing the wooden material and dry ice at a specified ratio, and after a compressed admixture has been obtained by compression-molding the admixture, an impact is impressed onto the compressed admixture so as to induce an abrupt sublimation/expansion of the dry ice and to impress, onto the wooden material, an impact ascribed to the expansion of the dry ice, as a result of which a woody fiber is prepared upon the fine fragmentation of the wooden material, and the finely fragmented woody fiber is recovered. The step of obtaining the compressed admixture is executed by spraying liquefied carbon dioxide onto the wooden material. The step of impressing an impact onto the compressed admixture is executed by inducing the collision, with the compressed admixture, of a preheated object.

Description

  The present invention relates to a method for producing a wood fiber, and more particularly to a method for producing a wood fiber of millimeter order to nanometer order.

  In general, it is known that various characteristics are expressed by, for example, nano-fabricating a substance. For example, in natural materials typified by cellulose, by converting the woody material into nanometer-order wood fibers (hereinafter sometimes referred to as “nanofibers” or “nanofibers”), the super specific surface area effect and nanosize effect are achieved. It is known that the supramolecular arrangement effect is expressed. The super specific surface area effect means that the specific surface area is several thousand to several tens of thousands times larger than that of a fiber having a diameter of a normal order. The surface area per unit weight increases dramatically as the fiber is made finer to the nanometer order, so that it has excellent properties such as “molecular recognition” and “adsorption properties”. Therefore, it is expected to be used for biofilters, sensors, and fuel cell electrode materials. The nano-size effect is an effect that results from having a nano-sized diameter, which creates “hydrodynamic properties”, “optical properties”, etc., and thus can capture submicron particles completely with low pressure loss. Expected to be used for ultra-high performance filters. Further, since the diameter of the nanofiber is smaller than the wavelength of light, irregular reflection of light is reduced, and a highly transparent fiber is produced. Therefore, the nanofiber is expected to be used for electronic paper having excellent light transmittance. Furthermore, the supramolecular alignment effect is an effect that results from the straight alignment of polymer chains, and produces “electrical characteristics”, “mechanical characteristics”, “thermal characteristics”, etc., resulting in conductive atoms and molecules. If the fibers are regularly arranged, it is possible to produce a fiber having excellent conductivity. Further, since the polymer chain is straight, the heat resistance is greatly improved.

  In addition, for micrometer-order wood fibers, which are on the order of a few tenths of wood fibers, the fiber structure and wood components retain the characteristics of wood fibers, and the unique characteristics of wood are utilized to provide rigid characteristics. have. For this reason, the fiber molded body easily forms voids and easily imparts lightness and heat insulation. Moreover, since the wood fiber has low thermal conductivity and hardly causes heat bridge, this property also contributes to the provision of heat insulation.

  As a method for producing such a fiber made of cellulose, a method by chemical treatment, a method by enzymatic hydrolysis, a method by mechanical treatment, and the like are known.

  As a method by chemical treatment, there are a method by TEMPO (2,2,6,6-tetramethylpiperidinooxy radical) oxidation treatment and a method by sulfuric acid treatment.

  In the method based on TEMPO oxidation treatment, as shown in Patent Document 1, by introducing a carboxyl group into a glucose unit in a cellulose molecule, an electrical repulsion effect between molecules is caused to separate cellulose nanofibers. In this method, cellulose nanofibers can be produced directly while removing lignin and hemicellulose from lignocellulose, and complicated pulping pre-processes such as “high temperature chemical treatment” and “multistage bleaching” can be omitted. Therefore, chemical / mechanical damage (decrease in crystallinity) of the nanofiber can be suppressed. Moreover, energy saving (manufacturing cost reduction) can be achieved, so that the burden on the environment can be reduced. Moreover, since it can process at normal temperature normal pressure, this can aim at cost reduction. Moreover, since it is a chemical treatment, there is an advantage that mechanical damage due to defibration can be minimized.

  In the method based on sulfuric acid treatment, as shown in Patent Document 2, the cellulose fiber is treated with sulfuric acid, and the amorphous cellulose is obtained by hydrolyzing and removing the non-crystalline portion, and the sulfate group introduced by the sulfuric acid treatment is obtained. It can be stably dispersed by electrostatic repulsion between each other. In the method of Patent Document 2, since nanofibers can be obtained from the waste liquid after hydrolysis in addition to hydrolysis treatment, there is an advantage that cellulose nanofibers can be produced efficiently.

  In the method based on enzymatic hydrolysis, as shown in Patent Document 3, cellulose nanofibers can be obtained by forming an amorphous part in cellulose microfibril (CMF) in advance and allowing endoglucanase to act on the amorphous part. It can be obtained efficiently. Since it can be carried out with simple equipment and mild conditions, cost reduction is expected, and the resulting cellulose nanofiber is less damaged. Moreover, since the permeability of the enzyme can be secured by forming the amorphous part in advance, there is an advantage that nanofibers can be obtained efficiently without using a large amount of enzyme.

  Examples of the mechanical treatment method include mechanochemical treatment, high-pressure homogenizer treatment, and counter-colonization treatment.

  In the method by mechanochemical treatment, as shown in Patent Document 4, after adding an affinity synthetic polymer as a grinding aid to a cellulose material, mechanical grinding such as a dry ball mill is performed. In addition, a bead mill, a disk mill, a hammer mill, a mixer, a homogenizer, or the like is used for mechanical pulverization. Pretreatment such as pressurized hydrothermal treatment causes swelling of cellulose and hydrolysis of hemicellulose, so that when the mechanical treatment is performed, the entanglement of the main components of the wood can be easily solved, and the cellulose nanofibers are highly efficient. There is an advantage that can be obtained.

JP 2008-308802 A Special table 2012-526156 gazette JP 2008-150719 A JP 2008-274247 A

  However, the method based on the TEMPO oxidation treatment disclosed in Patent Document 1 has a problem in that chemical modification occurs in cellulose itself because a carboxyl group is introduced into a glucose unit in a cellulose molecule. Nanofibers are obtained as a dispersion, but the solid concentration is limited to 5%. As described above, since the solid content is low and the amount of the liquid is large, there is a problem that it takes time to dry the nanofiber and the cost increases.

  Further, in the method using sulfuric acid treatment disclosed in Patent Document 2, since a vigorous reaction using a strong acid such as nitric acid treatment is performed, equipment that can withstand such intense reaction is required, and the cost of the equipment increases. There was a problem. In addition, since a large amount of sulfuric acid is required for the sulfuric acid treatment, there is a problem that the cost of the drug increases.

  In addition, the method using enzyme hydrolysis disclosed in Patent Document 3 has a problem that the reaction is not accelerated sufficiently because the enzyme is used, and the progress of the decomposition reaction is slow. In addition, since a large amount of enzyme is used, there is a problem that costs increase.

  Further, in the method by mechanical processing disclosed in Patent Document 4, since manufacturing unevenness is likely to occur, the processing time has to be long and the cost is increased because it has to be subjected to mechanical processing many times. was there. Moreover, since equipment for mechanical pulverization is required, there is a problem that costs increase in terms of equipment.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for easily and inexpensively producing high-quality woody fibers that do not undergo chemical modification.

As a result of intensive studies in view of the above problems, the present inventors have found that wood materials can be refined by impact force due to sublimation / expansion of dry ice. Also, since dry ice does not cause denaturation of wood materials, high-quality wood fibers can be obtained, and further, since dry ice sublimates directly from solid to gas without becoming liquid, it is refined. It has been found that other materials are not contained in the subsequent wood fibers, and that the wood fibers can be recovered without going through a post-process such as neutralization treatment, and the present invention has been completed.
That is, the present invention is a method for producing a wood fiber by fiberizing a wood material,
Mixing a wood material and dry ice at a predetermined ratio to obtain a mixture of the wood material and dry ice;
Compression-molding the mixture to obtain a compressed mixture;
A step of applying a shock to the compressed mixture to rapidly sublimate and expand the dry ice to give the wooden material a shock due to the expansion of the dry ice, thereby refining the wooden material to produce a wooden fiber When,
Recovering the refined wood fiber.

  In the method for producing a wood fiber according to the present invention, the step of obtaining the compressed mixture is performed by injecting liquefied carbon dioxide onto the wood material in one embodiment.

  Moreover, in the method for producing the wood fiber according to the present invention, in one aspect, the impact on the compressed mixture is performed by causing the compressed mixture to collide with an object at a high speed.

  In another aspect, impacting the compressed mixture is performed by consolidating the compressed mixture to form a lump and causing the lump to collide with an object at high speed.

  In the method for producing a wood fiber according to the present invention, it is preferable that the object is heated in advance.

  In particular, it is preferable that the object is a rotating body or a movable body, and the rotating body or the movable body is heated before the position where the compressed mixture collides at a high speed.

  Moreover, in the method for producing the wood fiber according to the present invention, in yet another aspect, impacting the compressed mixture is performed by causing the compressed mixture to collide against each other.

  Moreover, in the method for producing the wood fiber according to the present invention, in still another aspect, the impact to the compressed mixture is performed by rapidly exposing the compressed mixture to a high temperature condition.

  In the method for producing a wood fiber according to the present invention, it is preferable that the weight ratio of the wood material and the dry ice is 5: 1 to 1: 5.

  In addition, the method for producing a wood fiber according to the present invention may further include a step of pre-grinding the wood material before the step of obtaining a mixture of the wood material and dry ice.

  Further, in the method for producing a wood fiber according to the present invention, the object is a wood fiber collection container, and the mixture is made to collide with the collection container so that the wood material is refined and the refined wood is produced. It is preferred to collect the fibers.

  Moreover, it is preferable that the method for producing the wood fiber according to the present invention further includes a step of recovering carbon dioxide generated when the compressed mixture is collided.

  Moreover, in the method for producing a wood fiber according to the present invention, it is preferable that the wood fiber contains a cellulose fiber.

  According to the method of the present invention, since dry ice is used for the refinement of the wood material, it is possible to provide a method for easily and inexpensively producing high-quality wood fibers that are not subjected to chemical modification.

FIG. 1 is a diagram showing a pre-grinding step of a wood material. FIG. 2 is a diagram showing a process of producing a mixture of a wood material and dry ice. FIG. 3 shows a first embodiment of a technique for externally impacting the compressed mixture. FIG. 4 shows a second embodiment of the technique for applying an external impact to the compressed mixture. FIG. 5 shows a third aspect of the technique of applying an external impact to the compressed mixture. FIG. 6 shows a fourth embodiment of the technique for externally impacting the compressed mixture. FIG. 7 is a schematic view showing a collection container capable of performing the impact applying step and the wood fiber collecting step at the same time.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. However, the form shown below exemplifies a method for producing a wood fiber for embodying the technical idea of the present invention, and does not limit the present invention.

(Embodiment 1)
When the wood material 1 is made into fiber and the wood fiber 4 is produced, the wood material 1 and the dry ice 2 are mixed at a predetermined ratio to obtain a mixture 3 ′ of the wood material 1 and the dry ice 2, and the mixture 3 is compressed. The compression mixture 3 is obtained by molding. Then, by giving an impact to the compressed mixture 3, the dry ice 2 is rapidly sublimated and expanded to give the wooden material 1 an impact due to the expansion of the dry ice 2, thereby refining the wooden material 1 to obtain the wooden fiber 4 The produced and refined wood fibers 4 are collected. Before obtaining the compressed mixture 3 of the wood material 1 and the dry ice 2, you may further provide the process of pre-grinding the wood material 1. FIG. Moreover, you may further provide the process of collect | recovering the carbon dioxide generated when the compression mixture 3 is made to collide. Hereinafter, each process in the method of producing the wood fiber 4 will be described in detail.

  In the present invention, the wood fiber 4 means a fiber made of wood having a diameter of millimeter to nanometer, preferably a wood fiber having a diameter on the order of nanometer (hereinafter referred to as nanometer in this specification). A wood fiber having a diameter of the order is sometimes referred to as a nanofiber or a nanofiber, and in the present invention, if a part of the wood material is nano-sized and the part has a diameter of a nanometer order, it is referred to as a nanofiber. .)

(Wood material pre-grinding process)
FIG. 1 is a diagram showing a pre-grinding step of a wood material. First, the wood material 1 is prepared. The woody material 1 may be any material as long as it contains cellulose. For example, conifers such as cedar, cypress and pine, and broad-leaved trees such as birch, oak, hippopotamus and chestnut are listed as examples. It is done.

  Next, the wood material 1 is preliminarily pulverized by a crusher (not shown). The wood material after the pre-grinding is given the reference number 1A. The diameter of the wood material 1A after preliminary pulverization is preferably 1 μm to 3 mm, more preferably 1 μm to 300 μm, and even more preferably 1 μm to 50 μm. If the wood material 1 is pulverized to such a size in advance, it is possible to more efficiently perform the miniaturization described later. However, when using the wood material 1 that is fine to some extent from the beginning, it is not always necessary to perform preliminary pulverization. Whether or not to undergo the preliminary pulverization step may be appropriately determined based on the size of the wood material 1 to be used.

  In the preliminary pulverization, crushing devices such as a uniaxial crusher, a biaxial crusher, a hammer crusher, a refiner, a kneader, a disaggregator, a beater, a pulper, and a blower can be used. As a crushing apparatus used for preliminary crushing, any crushing apparatus may be used as long as the wooden material 1 can be crushed to a desired size.

(Wood material-dry ice mixture preparation process)
FIG. 2 is a diagram showing a step of producing a mixture 3 ′ of the wood material 1 and the dry ice 2 (wood material-dry ice mixture production step). Here, the wood material 1 includes not only the wood material 1 that has not been pre-ground, but also the wood material 1A that has been pre-ground as described above. The mixture 3 ′ of the wood material 1 and the dry ice 2 can be prepared by separately preparing the wood material 1 and the dry ice 2 and mixing them. Moreover, in another aspect, the mixture 3 'of the wooden material 1 and the dry ice 2 can be produced by spraying liquefied carbon dioxide (liquefied carbon dioxide gas) onto the wooden material 1. When the liquefied carbon dioxide is sprayed onto the wood material 1, the liquefied carbon dioxide cannot be liquid at normal pressure, and the liquefied carbon dioxide becomes a solid (dry ice 2). A mixture 3 ′ of material 1 and dry ice 2 is obtained.

  The mixing ratio of the wood material 1 and the dry ice 2 is preferably 10: 1 to 1:10, more preferably 5: 1 to 1: 5, by weight. If the mixing ratio of the wood material 1 and the dry ice 2 is within such a range, the wood material 1 can be efficiently miniaturized in the impact applying step described later.

(Production process of compressed mixture)
The mixture 3 ′ of the wood material 1 and the dry ice 2 is pressed and hardened as described above to form a compact compressed mixture 3. By pressing and solidifying the mixture 3 ′ in this way to obtain the compressed mixture 3, the contact area between the dry ice 2 and the wood material 1 is increased, and when the dry ice 2 is sublimated and expanded in the impact applying step described later, The impact force due to the expansion is transmitted well to the wood material 1, and the wood material 1 is made finer and finer.

  In the aspect in which the wood material 1 and the dry ice 2 are separately prepared and mixed to prepare the mixture 3 ′, it is preferable to add moisture to the raw material of the dry ice 2 when preparing the dry ice 2. When moisture is not included, the dry ice becomes powdery and it is difficult to press and harden the mixture 3 ′ of the wood material 1 and the dry ice 2. By adding a predetermined amount of moisture to the dry ice 2, a lump-like compressed mixture 3 can be produced instead of powder. The amount of water is preferably 0.01 g to 5 g, more preferably 0.01 g to 2.5 g, and still more preferably 0.01 g to 1 g with respect to 100 g of the mixture 3 '. If the amount of moisture is within such a range, the mixture 3 'can be pressed and solidified to form a block-like compressed mixture 3.

The compressed mixture 3 may be formed as described above, and this may be previously pulverized to produce a granular compressed mixture 3. Here, the granular compression mixture 3 means a compression mixture composed of substantially spherical particles having a diameter of 0.1 mm to 10 mm, more preferably a diameter of 0.1 mm to 5 mm, and still more preferably a diameter of 0.1 mm to 3 mm. A wooden material 1 and dry ice 2 are contained in the compressed mixture 3 having such a diameter. As described above, the compressed mixture 3 formed as described above is pulverized in advance, so that it is possible to satisfactorily impact the wooden material 1 when it is refined by applying an impact in a later step. 1 can be made finer.
When the compressed mixture 3 is pulverized in advance, a crushing device such as a hammer crusher, a refiner, a kneader, a roll mill, a wing mill, or a jaw crusher can be used.

Alternatively, the pellet-like compressed mixture 3 may be produced by extruding the mixture 3 ′ of the wood material 1 and the dry ice 2 mixed at the predetermined ratio described above. Here, the pellet shape is generally a cylindrical shape, but is not limited thereto, and includes a similar shape. The diameter of the pellet-shaped compressed mixture 3 is preferably 1 mm to 10 mm, more preferably 1 mm to 5 mm, and still more preferably 1 mm to 3 mm. Moreover, it is preferable that the height (longitudinal direction length) of the pellet-shaped compression mixture 3 is 1 mm-30 mm, More preferably, it is 1 mm-10 mm, More preferably, it is 1 mm-3 mm. When the pellet-like compressed mixture 3 has such a diameter and height (length in the longitudinal direction), as in the above case, when the impact is applied in the subsequent step and the material is refined, the wood material 1 is favorably impacted. The woody material 1 can be made finer and finer.
When producing the pellet-shaped compression mixture 3, it is not necessarily limited to the following, A general extrusion molding machine, a compression molding machine, etc. can be used.

(Impact application process)
3 to 6 are diagrams showing an impact applying step. The dry ice 2 is sublimated by applying an impact to the compressed mixture 3 of the wood material 1 and the dry ice 2 from the outside, whereby the dry ice 2 is rapidly expanded. The impact due to the expansion of the dry ice 2 is given to the wood material 1, and the wood material 1 is refined to become wood fibers 4.

  FIG. 3 shows a first embodiment of a technique for giving an external impact to the compressed mixture 3. In this embodiment, the dry ice blasting device 6 is filled with the compressed mixture 3, and the compressed mixture 3 is collided from the dry ice blasting device 6 with the high-pressure air to the object (for example, a plate of metal or the like) 8 at high speed. When the compressed mixture 3 of the wood material 1 and the dry ice 2 collides with the object 8 at a high speed, the dry ice 2 sublimes, and the volume of the dry ice 2 expands about 800 times during sublimation. The impact due to the expansion is transmitted to the wood material 1 included around the dry ice 2, and the wood material 1 is refined by receiving the impact.

  The ejection speed of the compressed mixture 3 onto the object 8 can be set to 100 to 500 m / s immediately after nozzle ejection, and is preferably about 100 to 350 m / s. When the firing speed is slower than 100 m / s, the compression mixture 3 is not pulverized and the wood fibers are not finely formed. Further, if the firing speed exceeds 350 m / s, the sound speed is exceeded, so a shock wave is generated and noise during processing becomes a problem. That is, if the firing speed is about 100 to 350 m / s immediately after nozzle ejection, the wood material 1 can be finely refined. The firing speed of the compressed mixture 3 to the object 8 is more preferably about 200 to 300 m / s immediately after the nozzle ejection, and if it falls within such a range, the wood material 1 can be further refined finely. .

  The object 8 may be any object, but more preferably is a plate of metal or alloy that can transfer heat. By heating the metal or alloy plate, the collision surface of the compression mixture 3 can be heated to a high temperature. If the compression mixture 3 of the wood material and dry ice collides with the high-temperature collision surface, the dry ice The energy of sublimation / expansion can be increased. Thereby, the impact by expansion | swelling becomes large and the wood material 1 can be refined | miniaturized more finely. The object 8 does not necessarily need to be heated, and the object 8 may be used at room temperature (specifically, 20 ° C. to 30 ° C.), and the compressed mixture 3 may collide with the object 8 at room temperature.

  FIG. 4 shows a second embodiment of the technique for giving an external impact to the compressed mixture 3. In the second aspect, the object 8 may be a rotating body that is formed in a hollow cylindrical shape by rolling a strip-shaped metal into a cylindrical shape and rotates about the central axis of the cylindrical object 8. The outer peripheral surface 10 of the cylindrical object 8 may be a collision surface, and the inner peripheral surface 12 of the cylindrical object 8 may be a collision surface. The heating means 16 may be arranged on the collision surface of the cylindrical object 8 on the lower side in the rotational direction of the position 14 where the compressed mixture 3 collides, and the object 8 may be heated at this position 18. When the cylindrical object 8 is rotated, the cylindrical object 8 is heated by the heating means 16 at a position 18 on the lower side in the rotational direction of the position 14 where the compressed mixture 3 collides, and then the heated portion rotates. The compressed mixture 3 collides with the heated part by rotating in the direction. By comprising in this way, since the compression mixture 3 can be made to collide with a hot collision surface, the impact by expansion becomes large. In addition, the heating of the object 8 and the collision of the compressed mixture 3 with the object 8 can be performed continuously, and good miniaturization can be performed. Furthermore, at the time of collision of the compressed mixture 3, the temperature of the object 8 can be kept constant, and the defibrating conditions can be kept constant. Moreover, since it heats with the heating means 16, the temperature fall of the object 8 by the collision of the compression mixture 3 containing the dry ice 2 can be suppressed, and dew condensation can be suppressed.

  Examples of the heating means 16 include a gas burner, an electric heater, a high frequency induction heating device, a dryer, and a boiling device.

  As shown in FIG. 4, the heating means 16 is provided outside the cylindrical object 8 (the heating means 16 provided outside the object 8 is indicated by a solid line) and is directed from the outside to the inside of the object 8. You may arrange. By providing the heating means 16 on the outside of the cylindrical object 8, heating can be easily performed because the heating means 16 does not come into contact with the column supporting the cylindrical object 8. Similarly, as shown in FIG. 4, the heating means 16 is provided inside the cylindrical object 8 (the heating means 16 provided inside the object 8 is indicated by a broken line), and the inside of the cylindrical object 8 is inside. You may arrange | position so that it may face outside. Space can be saved by providing the heating means 16 inside the cylindrical object 8.

  FIG. 5 shows a third aspect of the technique for giving an external impact to the compressed mixture 3. In the third aspect, the object 8 is a movable body on which a plate-shaped metal moves. One surface 20 of the plate-like object 8 may be a collision surface on which the compressed mixture 3 collides, and the other surface 22 may be heated by the heating means 16. Further, as shown in FIG. 5, one surface 20 of the plate-like object 8 may be a collision surface, and the other surface 20 may be heated by the heating means 16.

  As shown in FIG. 5, the position 18 adjacent to the position 14 where the compressed mixture 3 collides may be heated by the heating means 16, or only one of the two positions 18 may be heated. When the plate-like object 8 moves to the right side, the part heated at the left position 18 by the left heating means 16 is displaced to the position 14 where the compressed mixture 3 collides, and the compressed mixture 3 is moved to the heated part. Collide. On the other hand, when the plate-like object 8 moves to the left side, the part heated at the right position 18 by the right heating means 16 is displaced to the position 14 where the compression mixture 3 collides and is compressed to the heated part. Mixture 3 collides. By comprising in this way, the impact by expansion | swelling can be enlarged since the compression mixture 3 can be made to collide with a hot collision surface like the above. Further, similarly to the above, heating and collision can be performed continuously, and good miniaturization can be performed.

  The object 8 with which the compressed mixture 3 collides may be any object as long as it has impact resistance. Examples of the material constituting the object 8 include ceramic, metal, alloy, concrete, and the like. Particularly preferred is a metal as described above.

  Examples of the metal include copper, silver, gold, iron, aluminum, nickel, and the like because they have high impact resistance and thermal conductivity. Particularly preferred is copper. Examples of the alloy include stainless steel, solder, bronze, brass and the like. Particularly preferred is stainless steel.

  FIG. 6 shows a fourth embodiment of a technique for giving an external impact to the compressed mixture 3. In the fourth aspect, the compressed mixture 3 is caused to collide at high speed from two dry ice blasting apparatuses (not shown). Thus, by making the compressed mixture 3 collide with each other from the dry ice blasting apparatus, the impact force applied to the compressed mixture 3 is increased, and the compressed mixture 3 is easily pulverized. Therefore, the impact force due to sublimation / expansion increases, and the wood material 1 can be made finer and finer.

  The firing speed of the compressed mixture 3 at this time can be set to 100 to 500 m / s immediately after nozzle ejection, and is preferably about 100 to 350 m / s. When the firing speed is slower than 100 m / s, the compression mixture 3 is not pulverized and the wood fibers are not finely formed. Further, if the firing speed exceeds 350 m / s, the sound speed is exceeded, so a shock wave is generated and noise during processing becomes a problem. That is, if the firing speed is about 100 to 350 m / s immediately after nozzle ejection, the wood material 1 can be finely refined. The firing speed of the compressed mixture 3 to the object 8 is more preferably about 200 to 300 m / s immediately after the nozzle ejection, and if it falls within such a range, the wood material 1 can be further refined finely. .

  Moreover, in the 5th aspect of the method of giving an impact to the compression mixture 3 from the outside, the compression mixture 3 is exposed to high temperature conditions, and the dry ice 2 is sublimated rapidly. High temperature conditions mean 30 to 200 ° C. By exposing the compressed mixture 3 of the wood material 1 and the dry ice 2 to a high temperature condition and rapidly sublimating the dry ice 2, the impact due to sublimation / expansion is transmitted to the wood material 1 and the wood material 1 can be refined. Since the fibers are unwound by the expansion energy due to sublimation, an injection device such as a dry ice blasting device is unnecessary. When the compressed mixture 3 is exposed to a high temperature condition, it is important that the sealed container is depressurized and oxygen-free.

(Wood fiber recovery process)
Subsequently, the wood fiber produced by refining the wood material is collected. A suction device or the like is used to collect the wood fibers. Since the dry ice 2 sublimates into a gas when it collides with the object 8, after the compressed mixture 3 of the wood material 1 and dry ice 2 collides with the object 8, only the refined wood fiber 4 is alone. Exists. In other words, the dry ice 2 is sublimated and separated from the wood fiber 4. If the wood fiber 4 is sucked by the suction device, only the wood fiber 4 can be recovered.

In another aspect, a collection container 24 having a collision surface 14 as shown in FIG. 7 can be used. It is desirable that the collection container 24 be sealed so that carbon dioxide to be collected does not leak outside the collection container 24. If such a recovery container 24 is used, the impact applying step and the wood fiber recovery step can be performed simultaneously. The surface on the heel side of the collection container 24 corresponds to the collision surface 14, and the compressed mixture 3 is caused to collide with the collision surface 14 from the dry ice blast device 6 at a high speed. As a result, the dry ice 2 is sublimated and the wood material 1 is refined, and the refined wood fibers 4 are stored in the collection container 24, so that the wood fibers 4 are easily collected. The collection container 24 may include the above-described suction device.
It is preferable that water or hot water is poured into the collection container 24 and the water or hot water described above is present in the vicinity of the collision surface 14 on the heel side of the collection container 24. By adopting such a configuration, a part of the compressed mixture 3 that could not be sublimated after colliding with the collision surface 14 falls into water or hot water, so that the expansion energy of carbon dioxide is reduced to that of the wood material 1 or finer. It can be given to the wood fiber 4 and can be removed by sublimating the dry ice attached to the wood material 1 and the refined wood fiber 4 with water or hot water.

(CO2 recovery process)
Gaseous carbon dioxide generated when the compressed mixture 3 of the wood material 1 and dry ice 2 collides with the object 8 is recovered and reused. As a means for recovering carbon dioxide, a porous body, a gas suction device, a gas recovery device, a draft chamber, an absorption liquid, or the like can be used.

  In the aspect using the recovery container 24 described above, it is preferable that a part of the recovery container 24 is provided with carbon dioxide recovery means (not shown).

  As described above, according to the method according to the embodiment of the present invention, since dry ice 2 is used for the refinement of the wood material 1, high-quality wood fibers 4 that are not subjected to chemical modification can be easily produced. Can do.

1 Wood material 2 Dry ice 3 'Mixture 3 Compression mixture 4 Wood fiber (nanofiber, nanofiber)
6 Dry Ice Blasting Device 8 Object Colliding with Mixture 16 Heating Means

Claims (13)

A method for producing a wood fiber by fiberizing a wood material,
Mixing a wood material and dry ice at a predetermined ratio to obtain a mixture of the wood material and dry ice;
Compression-molding the mixture to obtain a compressed mixture;
A step of applying a shock to the compressed mixture to rapidly sublimate and expand the dry ice to give the wooden material a shock due to the expansion of the dry ice, thereby refining the wooden material to produce a wooden fiber When,
Recovering the refined wood fiber, and a method for producing the wood fiber.   The method for producing a wood fiber according to claim 1, wherein the step of obtaining the compressed mixture is performed by injecting liquefied carbon dioxide onto the wood material.   2. The method for producing a wood fiber according to claim 1, wherein the impact is applied to the compressed mixture by causing the compressed mixture to collide with an object.   The method for producing a woody fiber according to claim 1, wherein the impact is applied to the compressed mixture by solidifying the compressed mixture to form a lump and causing the lump to collide with an object.   The method for producing a wood fiber according to claim 3 or 4, wherein the object is preheated.   The method for producing a wood fiber according to claim 5, wherein the object is a rotating body or a movable body, and the rotating body or the movable body is heated before a position where the compressed mixture collides at a high speed.   The method for producing a wood fiber according to claim 1, wherein the impact is applied to the compressed mixture by causing the compressed mixture to collide against each other.   The method for producing a wood fiber according to claim 1, wherein the impact is applied to the compressed mixture by rapidly exposing the compressed mixture to a high temperature condition.   The ratio of the said woody material and the said dry ice is 5: 1 to 1: 5, The preparation method of the wood fiber in any one of Claims 1-8.   The method for producing a wood fiber according to any one of claims 1 to 9, further comprising a step of pre-grinding the wood material before the step of obtaining a mixture of the wood material and dry ice.   2. The method for producing a wood fiber according to claim 1, wherein the object is a wood fiber collection container, and the mixture is made to collide with the collection container to refine the wood material and collect the refined wood fiber. .   The method for producing a wood fiber according to claim 1, further comprising a step of recovering carbon dioxide generated when the compressed mixture is collided.   The method for producing a wood fiber according to any one of claims 1 to 12, wherein the wood fiber includes a cellulose fiber.

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