JPH05177610A - Wood meal and production thereof - Google Patents

Abstract

PURPOSE:To improve flowability and dispersibility by a method wherein wood meal is ground by a friction among grinding balls so that angular parts, projection, and the like of the ground wood meal are removed and, thereby, formed into wood meal particles having a high bulk specific gravity, and surface particles are applied to the wood meal particle. CONSTITUTION:For producing wood meal, e.g. first wood meal 110 as shown by a figure A, firstly raw wood 101 is ground into wood meal 102 of a required particle diameter by a grinder; the ground wood meal 102 is ground into wood meal particles 111 having a uniform surface shape and an improve bulk specific gravity by a friction among grinding balls; surface particles 112 separately prepared are fixed on the surface of the wood meal particle 111 by an external pressing force; and the wood meal 110 is completed. At this time, the ground wood meal 102 is supplied into a mill body 1, in which the grinding balls 3 of the great number are rotatively stirred by a motor 5 through a stirring bar 4. The ground wood meal 102 is taken out through a take-out port 7 to the external.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wood flour and a method for producing wood flour, and more specifically, it is used as a filler, a coloring material, etc. for plastic molded products, plastic sheets, plastic films, paints, etc. The wood powder having hard surface particles fixed on the surface, and a method for manufacturing the wood powder, and as a filler for paint, for example, an electromagnetic shield material,
The present invention relates to wood powder used for various conductive applications such as radio wave absorbers and antistatic materials, and a method for manufacturing wood powder.

[0002]

2. Description of the Related Art Conventionally, characteristics of natural wood, especially,
In order to obtain various plastic molded products, plastic sheets, plastic films (hereinafter simply referred to as plastic products) having surface characteristics similar to those of natural wood, and paints for various furniture and daily necessities. In order to give the same characteristics to the surface coating or film of the product, fine powder wood powder is applied to the plastic material of plastic products, the surface coating of furniture, daily necessities, etc., or the paint forming the film. Attempts to include it.

Further, regarding various products having surface characteristics similar to those of natural wood, the surface of the product is approximated to wood in order to effectively express the wood-like taste of this product. It is preferable to add a predetermined amount of pigment together with a predetermined amount of wood flour during molding of a plastic product, formation of a surface coating film, or film formation in order to simulate the required natural wood. I try to get the color tone.

Now, the wood powders and pigments used as fillers and coloring materials for plastic products and paints in the above-mentioned prior art will be described in more detail.

First, wood powder used as a filler for plastic products will be described. Conventionally, by using wood powder that has been pulverized into a fine powder as a filler for molding plastics, it is possible to eliminate distortion and the like that occur during molding of plastic products, and also to give the plastic products the required hardness and Attempts have been made to provide the plastic products with relatively high hygroscopicity and moisture releasing properties. Here, the wood powder used as a filler for the plastic molding does not agglomerate during handling, has good dispersibility in the plastic raw material, etc., and is further Improvements have been attempted so as to suppress the generation of wood acid gas.

As a conventional typical wood powder improved in this respect, there is, for example, a surface polishing powder in a particle board which is hardened with a urea resin. And
The main reason for using the above-mentioned particle board surface polishing powder is that the particle board surface polishing powder is fine and has a "grain" shape with relatively few cilia. That is, depending on the surface polishing means for the particle board, it is possible to easily obtain a fine and finely-powdered polishing powder having good lubricity, particularly a finely-powdered polishing powder having good dispersibility in the molding resin material of the plastic product. is there.

On the other hand, however, this type of particle board surface polishing powder is obtained because the material characteristics of the particle board itself, which is the object of polishing, do not have a homogenized average wood property. The resulting finely divided abrasive powder may not have the properties of a homogenized average wood. In addition, since the hard portion that accompanies the curing treatment with the urea resin is inherited by the resulting finely divided polishing powder, the inherent hygroscopicity and moisture release characteristic of ordinary wood flour can be achieved. There are problems such as chipping and lacking in the soft feel of wood flour.

From this point of view, conventionally, the raw material wood is mechanically broken by a cutter mill or the like, and is crushed by a crusher by impact, shear, or grinding means, for example, an impeller mill. It has been attempted to use a wood powder which is made into a fine powder and retains the moisture absorbing function and the moisture releasing function of the raw material wood itself.

Next, pigments used as coloring means for plastic products and resin coating films will be described.
Generally, a pigment is a fine powder mainly composed of an inorganic material or an organic material, and is used as an extender pigment in addition to the purpose of coloring a plastic product, a coating film of a paint or the like.

When such a pigment is used for coloring a plastic product, for example, heat resistance, insolubility in a solvent, etc. are generally required in consideration of plastic molding, and a molding resin for a plastic product is also required. There was a strong demand for effective dispersibility in materials. On the other hand, in the case of pigments used in paints, it is necessary that the pigments mixed in the coating liquid are well dispersed in the coating liquid without agglomerating by themselves, and moreover, they are easily dispersed in the coating liquid. It was required not to settle. In addition, pigments used for powder coating are required to have good fluidity in order to obtain effective mixing with, for example, epoxy resin powder.

In addition, a conductive filler for a paint, for example, an electromagnetic wave shielding material, a radio wave absorbing material, an antistatic material, or the like, which is used for a conductive film and is formed into a coating film, these various kinds of materials are used. As conductive fillers that give characteristics such as electromagnetic shielding and antistatic properties, fine powders of metals such as Ag, Cu, and Ni, fine powders of metal oxides such as SnO ₂ and ZnO, and fine carbon powders are available. Was used. Further, it has been required that each of these conductive fillers be uniformly dispersed and used in a coating liquid such as various resin paints.

Further, by using a fine powder of an inorganic material such as calcium carbonate powder as a filler for the plastic product, it is possible to provide the plastic product with desired dimensional stability and surface hardness. Was there.

[0013]

However, each of the above-mentioned conventional techniques has the following problems.

First, the surface-polishing powder of the particle board mentioned at the beginning is the resin coating when the polishing powder is used as a filler to obtain a plastic product by plastic molding or is mixed and dispersed in a resin paint. When a film was obtained, the obtained plastic product and coating film did not have a sufficient and uniform moisture absorption function, and there was a drawback that a sticky feeling was produced when the obtained plastic product and coating film were touched. In addition, the plastic products and coating films containing the surface polishing powder of the particle board have a hardened portion of the thermosetting resin possessed by the surface polishing powder on the surface of the plastic products and coating films, which is peculiar to wood. There is a disadvantage that a soft feel is not brought to these plastic products, coating films and the like.

Next, in the wood powder obtained by crushing the raw material wood by using a crusher such as an impeller mill which crushes by the action of impact, shear, friction, etc., various inherent peculiar characteristics of the wood itself, While the various functions are effectively retained, the resulting wood powder has horned parts, protruding parts, cilia-like beard parts, and many fibrous elongated wood powders are included. However, it has the disadvantage that it has extremely poor dispersibility in solvents such as paints and coating liquids, and that it cannot be uniformly dispersed in various plastic molding resin materials or sealing agents. Further, the wood flour thus obtained is liable to agglomerate in the process of crushing the wood flour and in the process of storing the wood flour obtained by crushing,
It is difficult to handle, and it has a drawback that it is agglomerated in the molding resin material of these plastic products or in the paint, especially during plastic molding or coating.

Further, the chips and sawdust as the raw material wood are not crushed by the action of impact, shear, friction or the like of an impeller mill, etc., and the chips and sawdust are crushed by a frictional action of, for example, a dry ball mill. When crushed using, the amount of long-fibrous wood powder occupied in the resulting crushed wood powder is large, while the crushed wood powder of fine powder particles is particularly over-crushed, and both wood powders mutually They had a tendency to aggregate and were difficult to use.

Next, regarding the pigment used in the paint for coloring, the particle diameter of the pigment is usually 1
It is around μm and very small.
The particle size of the secondary particles is about 0.1 μm to 0.5 μm.
Since the size is extremely small, the pigment is often not evenly dispersed when mixed and used with a molding resin solution for various plastic products, so that the plastic product does not develop color matching the added amount of the pigment. There was an inconvenience. Further, there is a problem in that the fine powder particles as the pigment are likely to aggregate with each other, and the aggregated pigment impairs the surface characteristics of the plastic product and causes color unevenness.

Further, as in the above, the pigment used is not uniformly dispersed in a solvent or solution such as a coating liquid or a coating liquid, and further, it precipitates in the solvent or the solution over time, so that There is a disadvantage that the color development corresponding to the added amount is not formed on the surface of the coating film. Further, similarly to the above, in this case, the fine powder particles as the pigment are likely to aggregate with each other, and the aggregated fine powder particles have a disadvantage that the surface characteristics of the coating film are impaired and uneven coloring occurs.

In addition, in the case of such a fine powder granular pigment having an extremely small particle diameter, when it is mixed with the above-mentioned epoxy resin powder or the like to perform powder coating, due to its poor fluidity,
There was also the inconvenience that these powders were not delicately mixed with each other, and the powders were in a quantitative lump state with each other.

Further, in the conductive filler for paint,
Usually, this is mixed and dispersed directly in the coating liquid in a state of having a particle diameter of about several μm, but even if this kind of conductive filler fine powder is stored, it is stored in the same manner as above. In the process of handling, addition to the coating liquid, and the process of compounding, there is a disadvantage that they tend to agglomerate and are not uniformly dispersed.

As a result, aggregates or the like of the conductive filler are exposed on the surface portion of the coating film to be formed, and the surface characteristics are impaired. As a result, for example, the surface of the coating film is corrugated or scratched. However, there is a problem in that such phenomena as generation, perforation at the agglomerate portion, and surface breakage occur, and the adhesion strength, abrasion resistance, water resistance, weather resistance, etc. of the formed coating film respectively decrease.

Further, since the fine powder of the conductive filler of this kind has a large weight as compared with its fine particle size,
When dispersed in a coating liquid, it tends to settle out over time and is likely to be unevenly distributed, and there is a disadvantage that the formed coating film is not homogenized together with the above tendency to aggregate.

In addition, the conductivity of the coating film itself containing the fine powder of the conductive filler is such that each of these defects has a great influence on the state of electrical coupling between the conductive fine powders. As the particle size of the conductive fine powder contained in the coating liquid becomes finer, it becomes necessary to increase the mixing ratio, and therefore the goodness of conductivity of the coating film obtained is relative to the adhesive strength. However, there was the inconvenience that the elasticity and other properties were reduced.

Furthermore, the calcium carbonate powder used as a filler in plastic products has poor dispersibility when mixed and dispersed in the molding resin material of plastic products, and the calcium carbonate powder is mixed in a solvent or solution. When dispersed and used, the calcium carbonate powder may settle out over time. As a result, the obtained plastic product has partially fleshy parts with different properties, and there is a disadvantage that the desired uniform dimensional stability and uniform surface hardness cannot be provided to the product. ..

In view of the inconveniences in the conventional example, the present invention has a good dispersibility in a molding resin material of a plastic product, a paint, and the like, and has hard surface grains immobilized on its surface. The purpose is to provide flour and a method for producing the wood flour.

Further, according to the present invention, surface grains having various characteristics and functions of the raw wood and having various functions on the surface, such as pigment, conductive material, inorganic material, metal material, plastic material, etc. By fixing the fine powder particles of, the wood powder having the various characteristics and functions of the raw wood itself and the characteristics and functions of the surface particles fixed to the surface, and the wood powder. It is intended to provide a manufacturing method of.

Further, according to the present invention, wood flour having an increased bulk specific gravity is used, and the wood flour having various functions is uniformly and surely immobilized on the surface portion of the wood flour. And to provide a method for producing the wood flour.

Further, according to the present invention, the wood grain capable of constantly maintaining the state in which the surface grain having various functions is thermally and chemically stable and fixed to the wood grain, The purpose is to provide a method for producing wood flour.

Further, according to the present invention, various pigments are effectively supported to have good color forming properties as a pigment, and in the treatment, handling and storage thereof, further, molding of a plastic product as an object. It is an object of the present invention to provide wood flour that does not aggregate at all when mixed and dispersed in resin materials and paints, and a method for producing the wood flour.

Further, in the present invention, as a conductive filler for a paint, the surface characteristics are modified so as to have good dispersibility in a coating liquid and the like and to give good conductivity to a coating film to be formed. It is intended to provide wood flour and a method for producing the wood flour.

Further, according to the present invention, as a filler or the like which effectively carries various inorganic fine powder particles such as calcium carbonate powder, the plastic product, which is the object, is further molded during the treatment, handling and storage thereof. It is an object of the present invention to provide wood flour that does not aggregate even when mixed and dispersed in resin materials, paints, and the like, and a method for producing the wood flour.

[0032]

In order to achieve the above object, the wood flour and the method for producing wood flour according to the present invention are configured as follows.

That is, the first invention of the present invention uses a crushed wood powder to be treated obtained by crushing raw wood, and the crushed wood powder to be treated is crushed by a frictional action between crushing balls to obtain a bulk material. A wood powder grain with an increased specific gravity and a plurality of surface grains that are smaller and harder than the wood powder grain with an increased bulk specific gravity are provided on each, and with respect to the surface portion of the wood powder grain with an increased bulk specific gravity. ,
The wood flour is characterized in that the plurality of surface particles are pressed and fixed by an external force.

The invention added to the first aspect of the present invention is a wood flour in which a plurality of surface grains are fixed to the surface portion of the wood flour grain having the increased bulk specific gravity, wherein the bulk specific gravity is enhanced. It is characterized in that the immobilization of the plurality of surface grains against the surface portion of the wood powder grain by the pressing external force is mainly a biting and binding of the plurality of surface grains to the surface portion.

Further, the immobilization is carried out by hugging bonds by the surface part including biting of a plurality of surface particles into the surface part, or by sandwiching a plurality of surface particles bite-bonded to the surface part by each other. It is at least one or more of a bond or a sandwiching bond between one or more surface grains that are bite-bonded to the surface part and one or more surface grains that are hug-bonded to the respective surface part. It is characterized by

The invention added to the first invention of the present invention is a wood flour in which a plurality of surface grains are fixed to the surface portion of the wood flour grain having the bulk bulk density enhanced, wherein the bulk bulk density is enhanced. A plurality of surface grains that are smaller and harder than the wood grain are mainly pigments or conductive materials.

The surface grain is characterized by being any inorganic material, plastic material, or metal material.

Further, it is characterized in that the surface particles are two or more kinds selected from pigments, conductive materials, inorganic materials, plastic materials and metal materials.

In a second aspect of the present invention, the crushed wood powder to be processed obtained by crushing raw wood is crushed by frictional action between the crushing balls to obtain wood powder particles having an increased bulk specific gravity. However, with respect to the surface portion of the pulverized wood powder to be treated which has an increased bulk specific gravity or the surface portion of the wood powder grain having an increased bulk specific gravity, the pulverized wood powder to be treated and the tree having an increased bulk specific gravity are used. The wood flour is characterized in that a plurality of surface grains smaller and harder than the powder grains are fixed by pressing external force.

The invention added to the second invention of the present invention is to increase the bulk specific gravity of the crushed wood powder to be treated by crushing by a frictional action between the crushing balls, In the surface portion of the wood powder particles having an increased bulk specific gravity, in the wood powder for fixing a plurality of surface particles, the crushed wood powder to be treated, or a plurality of the surface portions of the wood powder particles having an increased bulk specific gravity, The immobilization of the surface grains by the pressing external force is mainly characterized in that the plurality of surface grains are bite-bonded to the surface portion.

Further, the immobilization is carried out by hugging bonds of the plurality of surface particles including biting of the surface particles into the surface part, or sandwiching of a plurality of surface particles bite-bonded to the surface part by each other. It is at least one or more of a bond or a sandwiching bond between one or more surface grains that are bite-bonded to the surface part and one or more surface grains that are hug-bonded to the respective surface part. It is characterized by

The invention added to the second invention of the present invention is to increase the bulk specific gravity of the crushed wood powder to be treated by crushing by a frictional action between the crushing balls, while increasing the bulk density of the crushed wood powder to be treated. In a wood flour in which a plurality of surface grains are immobilized on the surface portion of a wood grain grain having an increased bulk specific gravity, a plurality of surface grains smaller and harder than the wood grain grain having an increased bulk specific gravity are mainly pigments, or It is characterized by being a conductive material.

Further, the surface grain is characterized by being any inorganic material, plastic material, or metal material.

Further, it is characterized in that the surface particles are two or more kinds selected from pigments, conductive materials, inorganic materials, plastic materials and metal materials.

A third aspect of the present invention uses a crushed wood powder to be treated obtained by crushing raw wood, and the crushed wood powder to be treated is crushed by a frictional action between crushing balls to obtain a bulk specific gravity. The step of forming an increased wood powder particles, the step of preparing a plurality of surface particles smaller and harder than the wood powder particles, the surface portion of the wood powder particles having an increased bulk specific gravity, by pressing external force And a step of fixing the plurality of surface grains, at least.

The invention added to the third invention of the present invention is a method for producing wood flour in which a plurality of surface grains are immobilized on the surface portion of the wood flour grain having an increased bulk specific gravity, wherein the bulk specific gravity is It is characterized in that the immobilization of the plurality of surface grains against the raised surface portion of the wood flour grain by pressing external force is mainly a bite bond of the plurality of surface grains to the surface portion.

Further, the immobilization is carried out by hugging bonds of the plurality of surface grains including the biting of the plurality of surface grains into the surface part, or by sandwiching the plurality of surface grains which are bite-bonded to the surface part. It is at least one or more of a bond or a sandwiching bond between one or more surface grains that are bite-bonded to the surface part and one or more surface grains that are hug-bonded to the respective surface part. It is characterized by

The invention added to the third aspect of the present invention is a method for producing wood flour in which a plurality of surface grains are immobilized on the surface portion of the wood grain grains having an increased bulk specific gravity. A plurality of surface grains that are smaller and harder than the elevated wood flour grains are mainly pigments or conductive materials.

Further, the surface grain is characterized by being any one of an inorganic material, a plastic material and a metal material.

Further, it is characterized in that the surface particles are two or more kinds selected from pigments, conductive materials, inorganic materials, plastic materials and metal materials.

A fourth invention of the present invention is to prepare a pulverized wood powder to be treated obtained by pulverizing a raw material wood and a plurality of surface grains smaller and harder than the pulverized wood powder, and a process for treating these pulverized wood powder. The crushed wood powder and a plurality of surface particles are supplied, and one of the crushed wood powders to be treated is crushed by the frictional action between the crushing balls to form wood powder particles having an increased bulk specific gravity. And at least a step of immobilizing the other surface grains on the surface portion of the pulverized wood powder to be treated or the surface portion of the wood powder grains having an increased bulk specific gravity by an external pressing force. It is a method of manufacturing wood flour.

In the invention added to the fourth invention of the present invention, the wood powder to be treated is ground by the frictional action between the grinding balls to form wood powder grains having an increased bulk specific gravity. In the method for producing a wood powder in which a plurality of surface grains are fixed to the surface portion of the treated pulverized wood powder or the surface portion of a wood powder grain having an increased bulk specific gravity, the treated pulverized wood powder, and It is characterized in that the surface grains are supplied in a state in which a plurality of surface grains are sprinkled and adhered to the crushed wood powder to be treated.

Further, the crushed wood powder to be treated and the plurality of surface particles are supplied to the crushed wood powder to be treated and the plurality of surface particles individually and simultaneously.

According to a fourth aspect of the present invention, the wood powder to be processed is ground by a frictional action between the grinding balls to form wood powder grains having an increased bulk specific gravity. A surface portion of the crushed wood powder to be treated, or a method for producing wood powder in which a plurality of surface grains are fixed to a surface portion of the wood powder grain having an increased bulk specific gravity, Alternatively, the immobilization of the plurality of surface grains against the surface portion of the wood powder grain having an increased bulk specific gravity by an external pressing force is mainly a biting bond of the plurality of surface grains to the surface portion.

Further, the immobilization depends on the hugging bond by the surface part including the biting of the plurality of surface particles into the surface part or between the plurality of surface particles bite-bonded to the surface part. At least one or more of pinch-bonding, or pinch-bonding by one or more surface grains that are bite-bonded to the surface part and one or more surface grains that are hug-bonded to the respective surface part. It is characterized by being.

According to a fourth aspect of the present invention, the wood powder to be treated is ground by a frictional action between the grinding balls to form wood powder grains having an increased bulk specific gravity. In the method for producing wood powder in which a plurality of surface grains are fixed to the surface portion of the crushed wood powder to be treated, or the surface portion of the wood powder grain having an increased bulk specific gravity, the crushed wood powder to be treated or the bulk specific gravity is The plurality of surface grains that are smaller and harder than the wood grain grains whose height is increased are mainly pigments or conductive materials.

Further, the surface grains are made of any inorganic material,
It is characterized by being either a plastic material or a metal material.

Further, the surface grains are pigments, conductive materials,
It is characterized by two or more kinds selected from inorganic materials, plastic materials, and metal materials.

In the second invention, the surface grains are
The bulk specific gravity is increased by the crushing due to the frictional action between the crushing balls. The crushed wood powder can be increased in the bulk specific gravity while being fixed or temporarily fixed on the surface of the crushed wood powder. The surface of the wood powder particles is different from that of the wood powder particles having the bulk specific gravity increased by the crushing by the frictional action between the crushing balls. And the case where the surface grains are fixed to the part.

Further, in the fourth aspect of the invention, in the treatment process of pulverizing wood powder to be treated by frictional action between the pulverizing balls to obtain wood powder grains having an increased bulk specific gravity,
The surface grains are fixed or once fixed to the surface portion of the pulverized wood powder to be treated during this treatment process, or the wood powder grain whose bulk specific gravity has already been increased by pulverization by the frictional action between the crushing balls. In this case, once the surface grains are once fixed on the surface portion of the crushed wood powder to be treated, the crushed wood powder is continuously crushed by friction between the crushing balls continuously applied to the crushed wood powder. The case of converting wood flour into wood flour grains having an increased bulk specific gravity is also included.

[0061]

[Function] Since the crushed wood powder to be treated is crushed by the frictional action between the crushing balls, the angular portion, the protruding portion, the ciliary beard portion, etc. of the crushed wood powder to be treated are It is removed and trimmed into a rounded shape as a whole, so-called "wood flour grains" with a higher bulk density.
Next, a supporting base material that fixes a plurality of surface particles to the surface portion,
Since it is a wood powder grain having a high bulk specific gravity or a wood powder grain partially containing crushed wood powder to be treated, it itself retains various properties and functions as a wood material, and Along with this, a plurality of surface particles fixed on the surface part cover the surface part of the wood powder particles having a higher bulk specific gravity as the supporting base material or the surface part of the crushed wood powder to be treated, or are almost covered. By forming a surface barrier against these wood powder particles and protecting the wood powder particles, the properties of the wood powder particles are substantially and effectively protected. At the same time, the obtained wood powder can easily be provided with good fluidity and compounding dispersibility as a filler. Moreover, the wood powder obtained at the same time surely brings various characteristics and functions of the surface grains.

[0062]

EXAMPLES Hereinafter, examples of wood flour and a method for producing wood flour according to the present invention will be described in detail.

FIG. 1 shows respective steps of forming a crushed wood powder to be treated from raw wood and immobilizing a plurality of surface grains on a surface portion of the crushed wood powder to be treated, to which an embodiment of the present invention is applied. The steps of forming wood powder particles from the crushed wood powder to be treated and immobilizing a plurality of surface particles on the surface portion of the wood powder particles, and the first and second wood powders to be constructed are respectively schematic. It is a schematic explanatory drawing shown in FIG. FIG. 2 is a schematic diagram showing an outline configuration of an open type dry ball mill according to an embodiment of the present invention for performing crushing wood powder to be treated and crushing wood powder particles by frictional action between grinding balls. FIG. FIG. 3 is a schematic diagram showing a schematic configuration of a hermetically sealed dry ball mill according to an embodiment of the present invention, which grinds wood powder to be treated and wood powder particles by frictional action between grinding balls. FIG. Figure 4
FIG. 1 is a vertical sectional front view of a main part showing a schematic configuration of a classifying device according to an example for classifying crushed wood powder to be processed and wood powder particles according to an embodiment of the present invention.

Prior to the detailed description of the embodiments according to the present invention, the main terms used in the description will be defined as follows. Regarding this definition, as mentioned above, since the size of the wood powder itself to be treated as an object of the invention is a very fine pulverized particle, it can be inferred to some extent regarding its action. In view of the unavoidable circumstances, the definition is not always the only constraint.

"Pulverization by frictional action between pulverizing balls" mainly means pulverization by the action of friction on an object to be pulverized using a ball mill, and is also referred to as "grinding" hereinafter. In the present specification, the "ball mill" refers to a mill that mainly stirs crushing balls vertically and circumferentially by a stirring means and crushes the crushing balls by friction between the crushing balls. It also includes other types of ball mills.

The term "wood flour particles" is a generic term for the above-mentioned crushed wood powder to be treated, in which the bulk specific gravity is increased by crushing due to the frictional action between the crushing balls. The angular portion, protruding portion, and cilia-like beard portion of the crushed wood powder to be treated are made into different shapes by the crushing due to the friction between the crushing balls, resulting in a higher bulk specific gravity. The wood flour is called "wood flour grain". Therefore, what is called "wood flour grain" here is a grain whose outer shape is mainly indefinite, and includes grains having a spherical shape or a shape similar to a sphere, but having a spherical shape or a shape similar to a sphere. It is not limited to grains.

That is, the "wood powder grains" as the wood powder having a high bulk specific gravity means that the bulk specific gravity of the crushed wood powder to be treated is crushed by friction between the crushing balls. It means all the wood powders that have been enhanced in a general way, and apart from the immobilization of the surface grains, the bulk specific gravity is increased by crushing only the crushed wood powder to be treated by the frictional action between the crushing balls. Of course, the wood powder being processed, for example, the surface portion of the crushed wood powder to be processed or the pulverized wood powder to be processed whose bulk specific gravity is being increased, while fixing the surface grains, to the crushed wood powder to be processed, By subjecting the crushing balls to pulverization by a frictional action, the powder specific gravity of the pulverized wood powder to be treated is substantially increased, and further, the pulverized wood powder to be treated or the bulk specific gravity is increased. Fixed surface grains on the surface of a certain crushed wood powder to be processed After that, the treated pulverized wood powder having the surface grains fixed thereto is pulverized by the frictional action between the pulverizing balls to increase the bulk specific gravity of the pulverized wood powder to be treated. It is a concept that also includes powder.

The bulk specific gravity here is, more specifically,
By crushing the crushed wood powder to be processed by the frictional action between the crushing balls, the outer surface shape is substantially adjusted, which is enhanced. The frictional crushing breaks the relatively elongated fibrous wood powder into a more granular shape, and the angular corners are removed by the frictional crushing between the crushing balls to give a rounded finish. It has a rounded shape, and the protruding part is removed by crushing due to the frictional action between the crushing balls, resulting in a rounded shape, and the cilia-shaped beard is crushed by the frictional action between the crushing balls. The part that has been removed and is relatively sparse due to intertwined cilia-like mustaches should be made relatively dense by crushing due to the frictional action between the crushing balls. Etc. Accordingly, the bulk density is increased substantially.

The "external pressing force" is a pressing force applied mainly by mechanical means from the outside of the surface portion, for example, as a suitable mechanical means thereof, the above-mentioned grinding, that is, compression and friction are involved. Means a pressing force or the like that occurs independently or in accordance with the crushing action.

"Immobilization" means fixing by a pressing force from the outside of the surface so as not to be easily peeled off, irrespective of chemical reaction or means such as adhesion.

The particle diameters of the crushed wood powder to be treated and the wood powder particles (Table 2, Table 3, Table 4, Table 5, Table 6 and Table 7) are, for example, those suspended in a predetermined solution. In the state of turbid dispersion, while individually guiding and passing through a transparent flow channel, by irradiating and transmitting laser light in the flow channel,
It refers to the particle diameter obtained by converting the numerical value obtained by measuring the length in the flowing direction into the diameter. Further, the particle size of the raw wood (Table 1) is such that when the raw wood is sieved for 5 minutes using a test vibration sieving machine (low tap), it passes through a large sieve mesh and a small sieve mesh. The raw wood remaining in No. 1 is indicated by the diameter of the mesh of the sieve.

The "average particle size" means 50% of the cumulative weight percent distribution of the crushed wood powder to be treated and the wood powder particles.
(Half amount) means the particle size in weight percent.

"Hardness" means, as described above,
Since the crushed wood powder to be treated and the wood powder particles or the surface particles are relatively extremely fine and it is difficult to directly measure their hardness, a unit expressing the hardness at the time of the raw material before crushing, for example, , In this case, it means Shore hardness.

The first wood powder and the second wood powder having a basic processed structure obtained by applying one embodiment of the present invention will be described in detail below with reference to FIG.

The first invention and the third invention of the present invention are
The first wood flour and the method for producing the first wood flour described in the following examples will be described specifically and in detail.

The second invention and the fourth invention of the present invention are more specific and detailed by the second wood powder and the method for producing the second wood powder as shown in the following embodiments. Explained.

In the first wood powder of this embodiment, a large number of the crushed wood powders to be treated are crushed by the frictional action between the crushing balls to adjust the outer surface shape to increase the bulk specific gravity. After forming each of the individual wood flour particles, a plurality of smaller and harder surface grains are fixed to the surface portion of each individual wood flour grain. In addition, the second wood powder of this example was prepared by crushing a large number of crushed wood powder to be treated obtained by crushing raw material wood and smaller and harder surface grains by the frictional action between the crushing balls. At the same time as the crushing treatment, the surface portion of each pulverized wood powder to be treated is constituted by immobilizing a plurality of respective surface grains, and ， After fixing, the bulk specific gravity of the crushed wood powder itself is increased with the crushing process which is continued by friction between the crushing balls,
It is composed by converting this into wood flour particles.

[First Wood Flour] First, a typical first method and a second method for obtaining the first wood flour 110 will be described.

A typical first method for obtaining the first wood flour 110 is shown in FIG. This first method first
In order to obtain the wood powder 110, first, the raw wood 101 is shocked,
By crushing using a crusher that crushes by the action of shearing, grinding, etc., the crushed wood powder 10 to be treated within the required particle size range
Get 2. Next, the crushed wood powder 102 to be processed is made into wood powder particles 111 whose surface shape is adjusted by crushing by the frictional action between the crushing balls and whose bulk specific gravity is increased. The wood powder particles 111 thus obtained and the surface particles 112 prepared separately are supplied to a pressing means for generating an external force, for example, a dry ball mill, and the surface particles 112 are pressed against the surface portion of the wood powder particles 111 by the external force. By fixing
First wood flour 110 is obtained.

A second typical method for obtaining the first wood flour 110 is shown in FIG. 1B. In order to obtain the first wood powder 110 by the second method, the wood powder particles 111 obtained by the first method are sprinkled with surface particles 112 or adhered by pre-mixing, and then the surface is obtained. The first wood powder is fixed by pressing the wood powder particles 111 having the particles 112 on the surface portion to generate external force, for example, a dry ball mill, and fixing the surface particles 112 on the surface portion to the wood powder particles 111. Get 110.

Then, the crushed wood powder 102 to be treated here
The wood powder grains 111 having an increased bulk specific gravity obtained by mechanically re-grinding the crushed wood are crushed from the crushed wood powder 102 to be processed, and thus the long-fiber crushed wood powder 102 to be processed is crushed. Is cut into a shape closer to a grain, and the angular portion and protruding portion of the crushed wood flour to be processed 102 are removed to make it roundish, and the shape is small due to removal of cilia-like mustache, Moreover, the raw material wood 10 can be made more granular and the bulk specific gravity can be increased.
1 Unique characteristics and functions of itself, such as hygroscopicity,
While keeping the moisture release and touch feeling,
Immobilization of the plurality of surface grains 112 on the surface portion is easily and surely performed.

The first wood flour 110 thus obtained
Is the surface grain 1 in contrast to the wood flour grain 111 having an increased bulk specific gravity.
Since 12 is pressed and fixed by an external force, the surface grains 112 of the first wood powder 110 are easily and uniformly fixed to the surface portions of the wood powder grains 111.

The first wood flour 1 thus obtained
10 is a surface grain 112, a wood flour grain 1 having an increased bulk specific gravity.
Since the surface grains 112 of the first wood powder 110 are fixed to the surface of the wood powder particles 11 by biting bonding or the like, the surface grains 112 of the first wood powder 110 can be reliably and uniformly formed on the surface parts of the wood powder grains 111 having an increased bulk specific gravity. Fixed.

Further, in the first wood flour 110 thus obtained, the bulk specific gravity of the wood flour grains 111 constituting the wood flour 110 is sufficiently increased, and the wood flour having the increased bulk specific gravity is obtained. Since the surface grains 112 are fixed to the surface portions of the grains 111, the resulting wood flour 110 has good fluidity, and when handling the wood flour 110, the wood flours themselves do not aggregate with each other. In addition, the dispersibility in mixing with a blending object such as paint is good.

Furthermore, since the surface grains 112 are fixed to the wood powder grains 111 by only pressing external force, the obtained first wood powder 110 is used in a solution, a solvent, or in a high temperature range. Also, the surface grains 112 are wood flour grains 111
Never separated from.

The first wood flour 1 thus obtained
The surface particles 112 of No. 10 are capable of exhibiting various functions and characteristics as the surface particles 112 in a state of being fixed to the surface portion of the wood powder particles 111. Compared with, the handling property is considered to be good.

Further, the surface grains 112 of the first wood flour 110 thus obtained cover the surface portions of the wood flour grains 111 as the supporting base material or almost cover them to form a surface barrier. Thus, the release of wood acid, lignin, etc. from the inner wood flour grain 111 can be prevented. Further, it has a function of withstanding the heat load from the outside and preventing invasion of undesired chemicals and the like, sufficiently protecting the wood flour grain 111, and effectively bringing its characteristics to the wood flour 110. ..

The first wood flour 11 thus obtained is obtained.
In 0, since the surface portion of the wood powder grain 111 is covered with the plurality of surface grains 112, the inherent low hardness of the wood powder grain 111 in terms of strength and low specific gravity are The surface grains 112 that cover the surfaces are relatively compensated and protected by the weight of the specific gravity and have sufficient hardness.

Moreover, since the wood powder grain 111 is relatively lightweight, it is possible to reduce the weight as a whole, and at the same time, it is possible to effectively and effectively use the wood scraps that have been relatively unutilized in the past. It can be utilized effectively to save resources.

Incidentally, the wood flour grain 1 in the first wood flour 110
11 and the particle size distribution of the particle size of the titanium oxide powder as the surface particles 112 fixed to the surface portion of the wood powder particles 111, the titanium oxide powder should also be ground during the fixing. Assuming that, the following may be roughly performed. Particle size distribution of wood powder particles Particle size distribution of titanium oxide powder 1 to 10 μm 0.2 to 3 μm 11 to 30 μm Same as above 1 to 5 μm

The hardness of the general raw material wood 101 as the wood powder grain 111 and the hardness of titanium oxide, carbon, nickel and calcium carbonate as the surface grain 112 harder than the raw material wood 101, The so-called Shore hardness, in which the indenter is dropped from a predetermined height and the rebound height after the collision is measured, is given below. Raw material Wood material 35-50 Titanium oxide 150-180 Carbon 60-65 Nickel 90-100 Calcium carbonate 120-140

[Second Wood Flour] Next, a typical first method for obtaining the second wood flour is shown by [C] in FIG.

In order to obtain the second wood powder 120 by the first method, first, the raw wood material 101 is broken and crushed by using a crusher that crushes by the action of impact, shear, friction, etc. To obtain the crushed wood flour 102 to be processed within the diameter range,
Next, the crushed wood powder 102 to be treated and the surface particles 122 are supplied to a crushing section by friction between the crushing balls, and the crushed wood powder to be treated is crushed by the friction between the crushing balls. The bulk specific gravity of 102 itself is increased, and at the same time, the crushed wood flour 102 to be treated or the wood grain 1
The crushed wood powder 102 in the process of 21 or the surface part 122 of the wood powder particles 121 whose bulk specific gravity has been increased by the crushing process by the frictional action between the crushing balls is the surface particles 122. Are fixed by a grinding process by a frictional action between the grinding balls. In the crushing process by friction between the crushing balls, the above-mentioned crushed wood powder 102 to be processed is a wood powder having a sufficiently increased bulk specific gravity by the crushing process between the crushing balls by friction. Continue until the state of grain 121 is reached. By the above, the second wood flour 120 is obtained.

Next, the second method for obtaining the second wood flour 120 is shown in FIG. In order to obtain the second wood flour 120 by this second method, the surface grains 122 are sprinkled or premixed on the crushed wood flour to be treated 102 obtained by the same means as the first method. After that, the crushed wood powder 102 to which the surface particles 122 are attached is crushed by friction between the crushing balls. The crushing process of the crushed wood powder 102 to be processed by friction between the crushing balls is performed by the crushed wood powder 1 to be processed 1
02 is continued until the state of the wood powder grains 121 whose bulk specific gravity is sufficiently increased by the crushing treatment by friction between the crushing balls, and further the crushing treatment by friction between the crushing balls is performed. By the surface grains 122
However, the process is continued until it is fixed on the surface portion of the wood powder grain 121 formed by the grinding process by the frictional action between the grinding balls. By the above, the second wood flour 120 is obtained.

The outer surface, and thus the surface shape, of the crushed wood powder 102 to be treated is gradually changed by the crushing by the frictional action between the crushing balls. , Its surface shape is substantially adjusted. This means that the treated wood flour 10
2 and the surface particles 122 are simultaneously supplied to a crusher for crushing by a frictional action between crushing balls, or after the surface particles 122 are sprinkled on the crushed wood powder 102 to be treated, this is supplied to the crusher. It is also recognized when crushing is performed by friction between the crushing balls.
The surface shape is adjusted in some manner, and as a result, the bulk specific gravity is increased. That is, it is added to the surface of the surface grains 122 by the grinding before the surface grains 122 are fixed, or by the pressing external force by the fixing of the surface grains 122, and further after the surface grains 122 are fixed. The surface shape is substantially adjusted by grinding or the like.

More specifically, the crushed wood powder 102 to be treated is crushed by the frictional action between the crushing balls to cut the crushed wood powder in the form of long fibers into finer particles. It is in a state close to. Further, the angular portion and the protruding portion of the crushed wood powder to be treated are removed by grinding, and the state becomes closer to a grain as a whole.
Also, the cilia-shaped beard portion of the crushed wood powder 102 to be treated is covered with the surface grains 122 from the peripheral surface of the crushed wood powder 102 to be treated, or the portion extending outward from the surface grains 122 is cut. To be done. Further, the surface portion of the crushed wood powder 102 to be treated is pressed and rolled by the crushing by the frictional action between the crushing balls, and the surface shape is adjusted.

The second wood flour 120 thus obtained
Is a wood powder grain 121 whose bulk specific gravity is increased by grinding the treated wood ground powder 102 by the frictional action between the grinding balls, and the surface of the wood powder grain 121 whose bulk specific gravity is increased. Since the surface particles 122 are fixed to the part, the surface particles 122 are reliably and uniformly fixed to the wood powder particles 121. Further, the obtained wood flour 120 has sufficient fluidity, the wood flours 120 do not aggregate with each other when the wood flour 120 is handled, and the dispersibility at the time of mixing with the object to be blended is good. is there.

Further, the surface grains 122 of the second wood flour 120
Is immobilized on the surface of the wood flour particles 121 in a manner that does not easily peel off. Moreover, since this immobilization is immobilization by pressing external force, the wood flour 120 is dissolved in a solution or solvent, or Even when used in the high temperature range, the surface particles 122 are not separated from the wood powder particles 121, and the surface particles 122 are stably held by the wood powder particles 121.

Further, the surface grains 12 of the second wood flour 120
2 exhibits various functions and characteristics of the surface grain 122 in a state of being immobilized on the surface of the wood grain 121,
The surface particles 122 can be used in a state in which they do not aggregate with each other. Further, the second wood flour 120 has various characteristics, such as hygroscopicity and moisture releasing property, which are obtained by breaking and crushing the raw material wood 101 by mechanical means so as to obtain various characteristics peculiar to the raw material wood 101 itself. , And the feeling of touch are retained, and the surface grain 122 allows the wood grain 1
Since the surface part 21 is covered or almost covered to form the surface part barrier, it has a function of effectively providing the wood flour 120 with various characteristics and functions of the raw material wood 101.

[Manufacturing means for the first wood powder and the second wood powder] Subsequently, the first wood powder 110 and the second wood powder 1
Details of manufacturing means 20 will be described.

Here, regarding each of the first wood powder 110 and the second wood powder 120, the crushed wood powder 102 to be treated in the formation process in the second wood powder 120 is substantially the first wood powder. Crushed wood powder 1 as a material used for wood powder 110
02, and also regarding the means for fixing the plurality of surface grains 122 to the surface portion of the second wood powder 120 and the form thereof, the plurality of surface grains 112 to the surface portion of the first wood powder 110. Since the means and the form of immobilization of the first wood powder 11 are almost the same as those of the first wood powder 11 in the following description.
0 mainly, and if necessary, the second wood flour 12
We will also describe 0.

In this embodiment, the kind of the natural wood which is the raw material to be crushed may be any of commonly used softwoods such as hemlock and lauan, and hardwoods,
Each raw material such as this wood, its chips, or its sawdust is used.

Of the raw materials, the raw material wood 101 such as wood and chips is first subjected to various known mechanical treatments such as a cutter mill and then various wood materials. It is cut and crushed without losing each function, and a large number of raw material materials having a particle size smaller than 1000 μm, preferably raw material materials having a particle size of 500 μm or less are prepared.

Further, the prepared raw wood 101 is subjected to a required pretreatment, if necessary. This pretreatment is usually carried out, for example, for bleaching the raw material having lignin or tannin, or an undesired pigment or resin content, or for removing unnecessary substances. Process by means.

Thereafter, as a crushing device, for example, a fine crusher for crushing by the action of impact, shearing, grinding or the like,
For example, by using an impeller mill to crush each of the raw material woods 101, similarly, it is preferable that the various properties and functions of the wood material are not lost in each case. The crushed wood powder to be processed 102 having a particle size of 200 μm or less is obtained.

In this case, the crushed wood powder 102 to be processed obtained by crushing the raw material wood 101 by the action of impact, shearing, grinding, etc., is, as described above, originally possessed by the wood itself. Although it retains its unique and peculiar characteristics and functions, it contains long fibers, and
A fibrous elongated ciliary beard is still derived from the peripheral surface.

Further, the obtained crushed wood powder 102 to be treated has many angular portions and protruding portions, is bulky as a whole, and tends to aggregate with each other. Here, as the crushing device used for the crushing, for example, an impact blade capable of adjusting the clearance between the crushing chamber and the corrugated liner, in this case, a rotor having an impact blade protruding in the radial direction of the circumference. Can be used.

By rotating the rotor at a high speed while adjusting the clearance of the impeller mill, the raw material wood 101 is crushed by impact breaking between the corrugated liner and the impact blade, and the impact blade itself also serves as the raw material wood. 10
1 is struck on the corrugated liner surface, similarly crushed and crushed to obtain crushed wood powder 102 to be treated.

The crushed wood powder to be treated 102 thus crushed may be used without classification, but it may be classified at the same time as the crushing or after the crushing, and the intended purpose of use. It is preferable to use the crushed wood powder to be treated 102 whose grain size is adjusted according to the above.

Further, the crushed wood powder 102 to be treated prepared as described above is prior to the crushing process by the frictional action between the following crushing balls, that is, the crushing process, or the process of the crushing process. Then, it is dried and adjusted so that the water content is less than 10 wt%, preferably less than 8 wt%, more preferably 3 wt% or less.

Here, the drying of the crushed wood powder to be treated 102 effectively causes the surface-modifying effect of the crushing treatment on the crushed wood powder 102 to be treated, and the object at the time of use. It has a meaning in preventing an adverse effect on an object such as a plastic product or a paint when the object is mixed and dispersed.

Subsequently, the crushed wood powder 102 to be treated, which has been treated as described above, is subjected to a grinding treatment by mechanical means, which is a re-grinding by a frictional action between grinding balls. In the first wood powder, the grinding process for the ground wood powder 102 to be processed is performed before the surface grains 112 are fixed.
The ground wood powder 102 to be processed is ground. The second wood flour is applied together with the surface grains 122 or with the surface grains 122 temporarily fixed or in a fixed state.

A typical means for this mechanical grinding process is the dry ball mill shown in FIG. Regarding the milling process by this dry ball mill, the formation of the wood powder grains 111 used for forming the first wood powder 110 will be described below.

In the grinding treatment of the crushed wood powder 102 to be processed by this dry ball mill, there is a fear that the temperature in the mill will rapidly rise and the explosion will occur due to the grinding treatment of the crushed wood powder 102 to be processed. In addition, since the properties and functions originally possessed by the wood powder to be ground or the wood powder particles having an increased bulk specific gravity are impaired by grinding in a high temperature range, the properties shown in FIG. As described above, by forming the cooling jacket 2 in the peripheral wall of the mill body 1, the water supply pipe 8 to the drain pipe 9 can be formed.
Cooling water is constantly supplied to the mill so that the temperature inside the mill is maintained at least 80 ° C. or lower, preferably 70 ° C. or lower.

Inside, there are arranged a stirring bar 4 as a stirring means which is rotationally driven by a motor 5, and a large number of intervening grinding balls 3 which are stirred and rolled by the stirring bar 4 to generate a grinding action. Then, the crushed wood powder 102 to be treated is put into operation from above and opened, and after the treatment is completed, it can be taken out from the take-out valve 6 through the take-out port 7 to the outside. To be done.

In this case, as the crushing ball 3 for obtaining the above-mentioned grinding action, a ceramic ball having a diameter of 3 mm to 15 mm is used, and avoiding the use of a stainless steel ball which may cause an explosion. ing.

In the dry ball mill having the above construction, however, the crushed wood powder 102 to be treated is fed into the mill.
Is crushed between the crushed balls 3 that are agitated and rolled, and the long-fiber-shaped crushed wood powder to be processed is broken and crushed by friction to be brought into a more granular state. Angular parts of powder, protruding parts, ciliary beard parts, etc. are removed or deformed,
The whole is arranged in a shape closer to a grain, and is rapidly heated to a required temperature due to frictional heat generated between each of these crushing balls 3 or between each crushing ball 3 and the crushed wood powder 102 to be treated. , The water content is removed, and 3 wt% to 5 wt% by continuing the grinding.
It is dried to a degree.

In this case, it is recognized that the crushed wood powder 102 to be treated has a tendency to be shrunk to some extent with the drying, and this shrinking tendency is also applied to the surface portion to be subsequently processed. The surface grains 112 are fixed, that is, the biting action is promoted.

Further, instead of the open type dry ball mill having the above-mentioned configuration, as shown in FIG. 3, a closed type dry type ball mill having a sealing lid 10, an exhaust pipe 11 and an air supply pipe 12 is arranged. A ball mill can also be used.

In the grinding treatment of the crushed wood powder 102 to be treated using this closed type dry ball mill, it is desirable that the oxygen concentration in the mill is within 15% and the temperature inside the mill is set at 80 ° C. or lower. In the case of a mill, after the crushing chamber in the mill is sealed by the sealing lid 10, the atmosphere in the crushing chamber is replaced with an inert gas, for example, nitrogen gas by using the exhaust pipe 11 and the air supply pipe 12, or the nitrogen gas is replaced with nitrogen gas. While flowing continuously,
This is operated under an inert atmosphere.

Further, as described above, the crushing process by frictional action between the crushing balls, that is, the crushing, that is, the crushing process, the outer shape is adjusted and the roundness is imparted to the whole, thereby increasing the bulk specific gravity of the tree. In order to classify the powder particles 111, for example, a classifying device shown in FIG. 4 can be used.

This classifying device is a wind-type specific gravity classifier for classifying by true specific gravity, and the centrifugal force generated by the rotation of the classifying rotor 13 by the motor 14 for the crushed wood powder 102 to be treated supplied from the direction of the arrow Y, It classifies under the balance of suction force of vacuum exhaust in the direction of arrow W, and takes out coarse powder that does not satisfy the classification condition in the direction of arrow X. Even in this classification operation, fine wood powder explodes in the device. In order to avoid the danger, nitrogen gas is continuously supplied into the apparatus from the direction of arrow N, and the apparatus is operated under an inert atmosphere while keeping the oxygen concentration within the apparatus within 15%.

The wood powder grain 111 thus obtained is
Grinding by frictional action between the grinding balls, that is, a wood powder grain 111 having an average particle diameter slightly smaller than the particle diameter of the ground wood powder 102 to be treated before the grinding treatment is used. Wood powder grain 111 is larger than the bulk specific gravity of the processed ground wood powder 102.
The bulk specific gravity of is increased, and before the grinding treatment, long-fiber-shaped crushed wood powder to be treated, angular portions, protruding portions,
A tree in which crushed wood powder to be treated having a ciliated beard portion and crushed wood powder to be treated having a relatively sparse portion have a relatively rounded surface after milling and have a smooth and dense surface condition. It is made into powder particles 111.

Here, concrete description will be given of individual experimental examples in each processing operation for obtaining the wood powder grain 111 and comparative examples thereof. (It should be noted that, as will be better understood in this Experimental Example and Comparative Example, for the objects having the same contents as in the above-mentioned Examples, for example, the raw material wood 101, the crushed wood flour 1 to be treated
02, wood flour grain 111, and wood flour 110 will be described with the same numbers. )

Experimental Example A-1. Sawdust of Ezo pine having the particle size distribution of Table 1 obtained by sieving, in this case, raw wood 101 as a raw material, using an impeller mill (model IMP-250 manufactured by Seishin Enterprise Co., Ltd.) And liner clearance 3mm
And crushed mechanically by the action of impact, shearing, grinding, etc. to obtain a crushed wood powder 102 to be treated having a particle size distribution shown in Table 2.

[0126]

[Table 1]

[0127]

[Table 2]

Further, the crushed wood powder 102 to be treated thus obtained was classified using the wind power type specific gravity classifier (PS separator manufactured by Powtech Co., Ltd.) shown in FIG. 4 to obtain the particle size distribution shown in Table 3. After obtaining the to-be-processed crushed wood powder 102, further, with respect to the classified to-be-processed crushed wood powder 102, a 5.4-liter capacity stirring bar loaded with 2.4 liters of zirconia-based ceramic crush balls having a diameter of 3 mm. Using a dry ball mill (Attritor A-200, manufactured by Mitsui Miike Kakoki Co., Ltd.) equipped with the above, this was pulverized by frictional action for 2 hours, that is, milled, and the particle size distribution of Table 4 in which the bulk specific gravity was increased. The wood powder grain 111 was obtained.

[0129]

[Table 3]

[0130]

[Table 4]

The wood powder grain 111 of the particle size distribution shown in Table 4 has an average particle size which is almost the same as that of the crushed wood powder to be treated 102 having the particle size distribution shown in Table 3, the particle size of which is slightly reduced and the bulk specific gravity is large. Was found to be increasing.

That is, the loose bulk specific gravity of the crushed wood powder to be treated 102 shown in Table 3 was 0.126 g / cc, and the solid bulk specific gravity thereof was 0.286 g / cc. The loose bulk specific gravity of the wood flour grains 111 shown in Table 4 is 0.186 g / cc, and the solid bulk specific gravity is 0.463.
It was g / cc, and it was confirmed that the bulk specific gravity of the wood powder grain 111 was significantly increased by the grinding treatment.

The loose bulk specific gravity here is 100.
The crushed wood powder 102 or wood powder particles 11 is placed in a cc container.
1 is sprinkled with a 24 mesh sieve to form a heap in a container, which is then scraped off, and the total weight of the crushed wood powder or wood powder particles in this container is divided by 100. There is. In addition, the bulk specific gravity of the solidified is 100 cc container that is subjected to vertical vibration (tapping vibration),
The processed pulverized wood powder 102 or the wood powder particles 111 are sprinkled while sieving with a 24 mesh sieve, and at the time when the change in the bulk of the pulverized wood powder 102 or the wood powder particles in the container due to the vibration is finished, the scraping is performed. , Crushed wood powder in this container 1
02 or the total weight of the wood powder grain 111 is divided by 100.

Further, in the crushed wood powder 102 to be treated before milling shown in Table 3, it is found that the dimension on the major axis side is longer than the dimension on the minor axis side. There are many wrinkled parts and cilia-like whiskers, but the wood flour particles 111 shown in Table 4 are almost granular as a whole and have roundness, and the surface is relatively smooth and dense. It was confirmed as a result of microscopic observation.

Then, the wood powder grain 111 thus obtained
Almost no coagulation occurs with each other, and the dispersibility in a solution is good, and is suitable as a support base material for pigments.

Experimental Example A-2. Sawdust of Ezo pine having the particle size distribution shown in Table 1 above, in this case, for the raw material wood 101 as the raw material, the same impeller mill as in Experimental Example A-1 was used for the raw material wood 101 as the raw material, and the impact blades of the crushing rotor rotated at high speed. The clearance between the liner and the liner is set to 3 mm, and this is crushed to obtain the crushed wood powder 102 to be treated, and then the crushed crushed wood powder 102 to be treated is zirconia-based with a diameter of 3 mm. A 5.4 liter capacity ball mill loaded with 2.4 liters of ceramic crushed balls (Mitsui Miike Kako Co., Ltd. Attritor A-200).
Was pulverized by a frictional action between the pulverizing balls for 2 hours, that is, pulverized to obtain wood powder grains 111 having a particle size distribution shown in Table 5, and the wind-type specific gravity classifier of FIG. (PS separator manufactured by Powtec Co., Ltd.) was used for classification to obtain wood powder grains 111 having a particle size distribution shown in Table 6.

[0137]

[Table 5]

[0138]

[Table 6]

Further, the wood powder grain 111 thus obtained
Is the angular portion of the crushed wood powder 102 to be treated,
As a result of microscopic observation, it was confirmed that the protruding part and the cilia-like beard part were removed, and the whole had roundness and the surface was relatively smooth and dense. ..

Moreover, these wood powder grains 111 are available in a relatively narrow range of particle diameters, have excellent fluidity and dispersibility, and are suitable for use as a support base material for pigments and the like. ..

Comparative Example A-1. A ball mill with a capacity of 5.4 liters (Atrita A-200, manufactured by Mitsui Miike Kakoki Co., Ltd.), in which 2.4 liters of zirconia-based ceramic grinding balls having a diameter of 3 mm were loaded with sawdust of Ezo pine having the particle size distribution shown in Table 1 above. Was ground by friction between the grinding balls for 2 hours, that is, ground.

In the wood flour thus obtained, an ultrafine powder wood flour portion and a long fiber-like portion are mixed, and 70 wt% or more remains with a particle diameter close to the original shape, and does not necessarily have a granular shape. It was confirmed that not. That is, the sawdust of Ezo pine is crushed using an impeller mill in advance to obtain the crushed wood powder 102 to be treated, and then, the above-mentioned experimental examples in which the bulk specific gravity is increased by means of friction, the direct grinding of the sawdust is included. When crushing, the crushing efficiency is extremely poor, and even if crushing for a long time, a large amount of long fiber-like parts remain, and on the other hand, there is a disadvantage that ultra-fine powdered over-ground wood powder is produced. The ultra-fine powdered over-milled wood powders were not suitable for use because they agglomerated with each other.

[Immobilization of Surface Grains in First Wood Flour] Next, the surface grain 112 having a smaller particle diameter and higher hardness than the surface portion of the wood flour grain 111 is immobilized. The details of the manufacturing method of the first wood flour 110 will be described.

Here, it is desirable that the wood powder particles 111 are arranged such that their respective particle diameters are within the finest particle diameter range. That is, when the compounding target is a paint for forming a coating film, it is preferable that the main part of the wood powder grain 111 has a particle size distribution included in a particle diameter range of 2 to 12 μm.

Also, the compounding object is a resin coating liquid,
Alternatively, when it is a molding resin material such as a plastic sheet or a plastic film, the wood powder grain 111 is 32
It is preferable that the particles have a particle size of less than or equal to μm, and it is more preferable that the particles have a particle size of less than or equal to 20 μm. Another more effective particle size distribution is
75 wt% or more of the total amount of particles with a particle size of 12 μm or less,
Preferably, it is desirable to occupy 80 wt% or more.

When the compounding object is a plastic product produced by injection molding or extrusion molding, each wood powder grain 111
Is preferably within a particle size range of 50 to 90 μm,
It is even more preferable that the particles have a particle size of 200 μm or less.

Further, when the compounding object is a product such as a plastic sheet which is kneaded and molded by a molding means such as a calender roll, it is larger than the particle diameter used by being compounded with the molding resin material of other plastic products. It is possible to use wood powder grains 111 having a particle size.

Next, regarding the immobilization of the surface grains 112 on the surface portion of the wood flour grain 111, that is, the immobilization by the pressing external force, the bulk specific gravity of the wood flour grain 111 is applied by the pressing external force applied from the outside of the surface. The surface of which the height is increased is subjected to grinding treatment or various mixers which generate external pressing force.

[0149] Here, the surface grain 11 against the wood grain 111
2 is fixed primarily by a bite bond. In this bite-in bonding, the surface grains 112 often interfere with each other, such as when the surface grains 112 interfere with each other, and because the grinding process causes heat generation. In accordance with the bite-in bond of the surface grain 112 to the part, the hugging bond is performed by the surface part, or the bite-in surface grain 1 which is the bite-in bond.
12 mutual or bite-bonded surface grains 112
By this, the sandwiching and bonding between the surface grains 112 and the hugging-bonded surface grains 112 are performed, and in this case, the effect which is combined with some condensing and contracting action by cooling after the completion of the processing operation is remarkable. The immobilization can be achieved by a strong and extremely strong immobilization, that is, by immobilization by neither chemical reaction nor adhesion.

The surface grain 11 against the wood grain 111
The immobilization of No. 2 may be performed by simultaneously supplying the wood powder particles 111 and the surface particles 112 to a device for generating an external force, such as a dry ball mill. Further, the surface grain 112 is attached to the surface of the wood grain 111 in advance, and by such pre-mixing, the wood grain 111 is prepared by temporarily holding the surface grain 112 on the surface. The powder particles 111 may be pressed and supplied to a device that generates an external force, for example, a dry ball mill or the like, and the surface particles 112 on the surface portion may be bite into and bonded to the wood powder particles 111.

The surface grain 112 may be fixed to the surface of the wood grain 111 by covering the whole surface of the wood grain 112, or by covering only a part thereof. Is also good. Further, the surface grains 112 may be fixed so as to overlap each other and cover the surface portions of the wood flour grains 111 in layers.

[Immobilization of Surface Grains in Second Wood Flour] Next, crushed wood flour 1 to be treated in the second wood flour 120.
02 or immobilization of the surface grains 122 on the wood flour grains 121 will be described.

Wood grain 12 in this second wood flour 120
The surface grain 122 is fixed to the first wood powder 1
In the process of obtaining 10 wood powder particles 111, the surface particles are simultaneously fixed. The apparatus used, the molding means for the wood powder particles 121, and the fixing means for the surface particles 122 are all the first wood particles. It is similar to the case of the powder 110.

The second wood flour 120 is prepared by crushing raw wood, crushed material of chip material with a cutter mill, sawdust, etc. using a crusher, for example, an impeller mill, and arranging them to the required particle size. The crushed wood powder 102 to be processed,
A process for increasing the bulk specific gravity of the crushed wood powder 102 to be treated by using a crushing means for grinding the surface particles 122, for example, a dry ball mill. Surface grain 1 on the surface of the wood grain 121
It is obtained by performing two types of processes, i.e., a process of fixing 22 and a process of simultaneously advancing.

Therefore, the surface grains 122 are fixed or tentatively fixed to the surface portion of the crushed wood powder 102 to be treated or the surface portion of the crushed wood powder 102 having a high bulk specific gravity. While increasing the bulk specific gravity of the wood flour 102, as a result, this wood flour grain 121 with an increased bulk specific gravity
When fixed to the surface portion of the wood powder particles 121, the surface particles 122 are added to the wood powder particles 121 whose bulk specific gravity has already been sufficiently increased by the grinding treatment applied to the crushed wood powder 102 to be treated. On the other hand, it may be fixed by the pressing external force by this grinding treatment.

In any case, the surface grain 122 is fixed to the surface portion of the wood flour grain 121 whose bulk specific gravity is consequently increased to form the second wood flour 120.

Surface grain 12 in this second wood flour 120
The immobilization of No. 2 is the same as the immobilization of the surface grains 112 in the first wood flour 110 described above. The interlocking bond between the surface grains 122 that are bound together and the surface grains 122 that are bound together is used as the main binding means.

Regarding the immobilization treatment of the second wood flour 120, when it is necessary to arrange the particle diameters of the second wood flour 120 as the final treated product, the crushed wood flour 10 to be treated is treated.
It is preferable to classify the particles 2 within a predetermined range by once classifying the particles 2 and then supply the particles with a plurality of surface particles 122 into the processing apparatus. When it is not always necessary to prepare, it is sufficient to perform without classifying. It should be noted that the surface grains 1 with respect to the surface portion of the crushed wood flour 102 or the wood flour grain 121 as described above
22 is fixed by this crushed wood powder 102 or wood powder grain 1
21 may be configured to cover the entire surface of the surface portion,
It may be designed to cover only a part. Further, the surface grains 122 are overlapped with each other so that the crushed wood powder 102 to be treated is
Alternatively, the surface portion of the wood powder grain 121 may be fixed so as to cover the surface portion thereof in layers.

[Each surface grain] Next, wood flour grains 111, 12
The surface grains 112 and 122 fixed to the surface portion of No. 1 will be described.

The surface particles 112 and 122 may be any of various pigments, various inorganic materials, various metal materials, various plastic materials, various conductive materials, and the like. That is, the surface grains 112 and 122 are the same as the wood grain 11
1, 121 (in the second and fourth inventions, the crushed wood powder 102 to be treated is also included), any material can be used as long as it has hardness and size that can be bitten into the surface. it can.

The surface grains 112 and 122 have properties corresponding to the uses of the wood powders 110 and 120, respectively. Generally, wood flour 11
When 0 and 120 are mixed with a molding resin material for plastic products, paints, etc., the surface grains 112 and 122 of the wood powders 110 and 120 are chemically and thermally stable. It is preferable to use those which do not impair the characteristics or have any adverse effect on the formed plastic products, coating films and the like.

[Wood Flour Having Inorganic Material Particles] Then, the grain material of the inorganic material is used as the surface particles 112 and 122, and the wood powder grain 1 is used.
The wood flour 110, 120 fixed to 11, 121 will be described.

The inorganic material used for the surface grains 112, 122 has a hardness higher than that of the wood powder grains 111, 121 and the crushed wood powder 102 to be treated, and the wood powder grains 111 are , 121 and crushed wood flour 10 to be treated
It has a specific condition that the particle size is relatively small corresponding to the particle size of No. 2, and is selected from various inorganic materials in consideration of usage conditions in the compounding target.

Particles of wood flour grain 111 and wood flour grain 121 (in this case, as crushed wood flour to be treated 102) having an inorganic material typified by the fine powder of calcium carbonate as surface grains 112 and 122. The diameter is wood flour 110,
120 particles, for example, plastic sheet, plastic board, various extrusion molded articles, injection molded articles, etc., usage, for example, application, injection molding, extrusion molding, roll molding, etc. It is preferable to arrange the range of.

For example, when the compounding object is a plastic film, a plastic sheet, etc., wood powder grain 1
11. In the second wood powder 120, the crushed wood powder 102 to be processed is 3
The particle size is preferably 2 μm or less, more preferably 20 μm or less. Further, as another effective particle size distribution, it is desirable that particles having a particle size of 12 μm or less account for 75 wt% or more, preferably 80 wt% or more of the total amount.

Further, when the compounding object is a plastic product such as injection molding or extrusion molding, the wood powder grain 11
In the first and second wood powders 120, the processed wood powder 102 is 50
The particle size is preferably in the range of from 90 to 90 μm, and 200
It is even more preferable that the particles have a particle size of less than μm.

When the compounding object is a molded product such as a plastic sheet which is kneaded and molded by a molding means such as a calender roll, it is possible to use one having a larger particle diameter.

Next, with respect to the surface portions of the wood powder particles 111, 121 and the crushed wood powder 102 to be treated, surface particles 112, 1
The means for supporting inorganic material particles such as calcium carbonate powder as 22 may be exactly the same as in the case of obtaining the above-mentioned first wood powder 110 and second wood powder 120. It is preferable that the wood powder particles 111 and 121 as the base material are embedded in and fixed to the surface portions by covering them.

The wood powders 110 and 120 obtained in this way provided good dimensional stability to plastic boards and the like, and the expansion and contraction due to temperature change were extremely small.

Then, a plurality of surface grains 112 are formed on the surface portions of the wood grain particles 111, 121 and the crushed wood grain 102 to be treated.
Each experimental example in the processing operation for fixing the fine particles of calcium carbonate as 122 to obtain the wood flours 110 and 120 will be specifically described. (It should be noted that, for better understanding of this experimental example, for the objects having the same contents as those in the above-mentioned example, for example, the raw material wood 101 and the crushed wood flour 10 to be treated are used.
2, the wood flour grains 111 and 121, and the wood flour 110 and 120 are attached with the same numbers for description. )

Experimental Example B-1. Sawdust of Ezo pine having the particle size distribution shown in Table 1 above, in this case, each raw wood material 1
For No. 01, as in the above, using an impeller mill (IMP-250 manufactured by Seishin Enterprise Co., Ltd.), the clearance between the impact blade and the liner of the crushing rotor rotating at high speed was set to 3 mm, and the impact, shear, and abrasion were set. Pulverized by the action of crushing, etc.
Got

The crushed wood powder 102 thus obtained was classified to obtain the crushed wood powder 102 having the particle size distribution shown in Table 3 above, and then the classified crushed wood powder 102 was further treated. For the crushed wood powder 102, a 5.4 liter capacity dry ball mill (Attritor A-200 manufactured by Mitsui Miike Kakoki Co., Ltd.) loaded with 2.4 liters of zirconia-based ceramic crushed balls having a diameter of 3 mm was used. Grinding treatment was carried out for a period of time to obtain wood powder grains 111 having a particle size distribution shown in Table 4 having an increased bulk specific gravity.

Further, 1.5 kg of the surface grains 112 are added to the 1.5 kg of wood powder grains 111 thus obtained.
After adding and dusting the calcium carbonate fine powder particles, wood powder grains 111 sprinkled with the calcium carbonate fine powder are similarly mixed using a dry ball mill (Mitsui Miike Kakoki Co., Ltd. Attritor A-200). Then, wood flour 110 was obtained by fixing the finely divided calcium carbonate particles on the surface as expected.

A sheet made of vinyl chloride resin was obtained by using the wood powder 110 thus obtained as a filler. The vinyl chloride resin sheet contained the wood powder 110 in a uniform manner, had no sticky feeling on the surface of the sheet, and had significantly less expansion and contraction due to temperature change.

Experimental Example B-2. Sawdust was crushed using an impeller mill (IMP-250 manufactured by Seishin Enterprise Co., Ltd.) to obtain crushed wood powder 102 to be treated having a particle size distribution shown in Table 7.

[0176]

[Table 7]

1 kg of the crushed wood powder 102 to be treated was prepared, and 0.7 kg of fine particles of calcium carbonate as the surface grains 122 were sprinkled on the powder, followed by dry ball mill (Attritor A-200 manufactured by Mitsui Miike Kakoki Co., Ltd.). ) Was used to grind the crushed wood powder 102 to be treated, which had been sprinkled with fine particles of calcium carbonate, for 2 hours.

By the grinding treatment with this ball mill,
At the same time that the surface shape of the crushed wood powder to be treated 102 was adjusted, fine powder particles of calcium carbonate were carried on the surface portion of the wood powder particles 104 whose surface shape was adjusted, and the wood powder 120 was obtained. .. Then, the wood flour 120 obtained here
Was used as a filler, and a vinyl chloride resin rod was obtained by extrusion molding.

[0179] The bar material obtained in this step is made of wood flour 120
Was included in a uniform manner, there was no sticky feeling on the surface of the bar material, and the expansion and contraction due to temperature change was extremely small.

[Wood Flour Having Pigment Particles] Next, the pigment particles as the surface grains 112 and 122, and the wood flour grain 11
The wood powders 110 and 120 in which the pigment particles are fixed to the surface portions of Nos. 1 and 121 will be described.

As described above, the pigment particles used for the surface particles 112, 122 have a hardness higher than that of the wood powder particles 111, 121 and the crushed wood powder 102 to be treated. And has a specific condition that the particle diameter is relatively small corresponding to the particle diameters of the wood flour grains 111 and 121 and the crushed wood flour to be treated 102, and the use conditions in the compounding target, particularly heat resistance All pigments can be used regardless of whether they are inorganic pigments or organic pigments, in addition to consideration of properties and the like.

Then, wood powder particles 111 and 121 carrying pigment particles as the surface particles 112 and 122.
(In this case, the crushed wood powder to be treated 102) is preferably arranged in a particle size range as fine as possible.

That is, when the object to be blended is a paint for forming a coating film, in the wood powder grain 111 and the second wood powder 120, the main part of the crushed wood powder to be treated 102 is in the particle diameter range of 2 to 12 μm. It is preferable that the particle size distribution is within the range.

When the compounding object is a paint or a plastic material such as a plastic film or a plastic sheet, the wood powder grains 111 and the second wood powder 12 are used.
In No. 0, it is preferable that the crushed wood powder 102 to be treated has a particle size of 32 μm or less, and more preferably 20 μm or less by classification. Still another effective particle size distribution is that particles having a particle diameter of 12 μm or less occupy 75 wt% or more, preferably 80 wt% or more of the total amount.

Further, when the compounding object is a plastic injection molded product, an extrusion molded product, etc., wood powder particles 11
In the first and second wood powders 120, the processed wood powder 102 is 50
The particle size is preferably in the range of from 90 to 90 μm, and 200
It is even more preferable that the particles have a particle size of less than μm.

When the compounding object is a plastic sheet or the like which is kneaded and molded by a molding means such as a calendar roll, it is possible to use one having a larger particle diameter.

Next, with respect to the surface portions of the wood powder particles 111, 121 and the crushed wood powder 102 to be processed, surface particles 112, 1
The means for supporting the pigment particles as 22 may be exactly the same as in the above-mentioned embodiment, and the pigment particles are fixed by being bite-bonded to the surface portions of the wood powder particles 111, 121 as the carrier base material. It is preferable that the surface portion is converted into a solid and the surface portion thereof is completely covered.

The pigment particles as the surface grains 112 and 122 are those whose amount is appropriately set according to the desired shade of coloring, and the wood powder carrying the pigment particles thus obtained is carried out. In 110 and 120, it was confirmed that the color tone exhibited was almost the same as that of the pigment particles to be blended, and that it had good fluidity.

Further, in the injection molding and the extrusion molding in which the wood powders 110 and 120 carrying the pigment particles thus obtained are mixed and dispersed in the plastic molding material, both molding pressures are low, and the molded products are The mixed pigment is uniformly dispersed therein, and no uneven color is observed.

Subsequently, the surface grains 112, 12 are formed on the surface portions of the wood flour grains 111, 121 and the crushed wood flour 102 to be treated.
Experimental examples in each processing operation for fixing the pigment particles as No. 2 to obtain the wood powders 110 and 120 will be specifically described. (It should be noted that, for better understanding of this experimental example, for the objects having the same contents as those of the above-mentioned example, for example, the raw wood 101, the crushed wood powder 102 to be processed, the wood powder grains 111,
21 and wood flour 110, 120 will be described with the same numbers. )

Experimental Example C-1. Sawdust of Ezo pine having the particle size distribution shown in Table 1 above, in this case, each raw wood material 1
For No. 01, similarly to the above, using an impeller mill (IMP-250 manufactured by Seishin Enterprise Co., Ltd.), the clearance between the impact blade and the liner of the crushing rotor rotating at high speed was set to 3 mm, and the impact and grinding means was used. Crushed wood powder mechanically, and the crushed wood powder 102 to be treated having the particle size distribution shown in Table 2 above.
Got

[0192] Further, each of the ground pulverized wood powders 102 thus obtained was classified to obtain the pulverized wood powder 102 to be processed having the particle size distribution shown in Table 3 above, and then the classified wood powders 102 were further classified. Regarding the treated ground wood powder 102, in the same manner as described above, a dry ball mill of 5.4 liter capacity (Attritor A-2 manufactured by Mitsui Miike Kakoki Co., Ltd.) loaded with 2.4 liters of zirconia-based ceramic crushed balls having a diameter of 3 mm.
00) was milled for 2 hours to increase the bulk specific gravity.
Got

Further, the wood powder grain 111 thus obtained
1 kg was prepared, 0.7 kg of titanium oxide particles as pigment particles were added to the wood powder 111 and sprinkled, and then the titanium oxide particles were applied to the surface of the wood powder particle 111 using the same ball mill as described above. The wood powder 110 was obtained by fixing.

As a result of observation with a micrograph, the wood powder 110 having the titanium oxide particles thus obtained fixed on the surface was found to be oxidized as pigment particles on the surface of the wood powder grain 111 as the carrier base material. It was confirmed that the titanium particles were held in a state of being bitten. Then, the entire wood powder 110 has a white color which is the background color of the titanium oxide particles,
Both fluidity and dispersibility in solution were good. Further, the plastic board molded by using this wood powder 110 as a pigment showed particularly small expansion and contraction due to temperature change.

Experimental Example C-2. 1.5 kg of crushed wood powder 102 to be treated having the particle size distribution of Table 7 obtained by crushing sawdust with an impeller mill (IMP-250 manufactured by Seishin Enterprise Co., Ltd.) was prepared, and titanium oxide as surface grains 122 was prepared. 1.5 kg of fine powder particles were prepared, and titanium oxide fine powder particles were sprinkled on the crushed wood powder 102 to be treated, and then a dry ball mill (Mitsui Miike Kako Co., Ltd. Attritor A-200).
The crushed wood powder 102 to which the fine particles of titanium oxide were sprinkled was subjected to a grinding treatment for 2 hours.

With the grinding treatment by this ball mill,
The crushed wood powder 102 to be treated had the corner portions and the protruding portions removed, and the ciliated beard portions were removed, and the wood powder particles 121 had a grain-like shape as a whole.

Further, in the wood powder 120 obtained here, it was found that the fine particles of titanium oxide were fixed in the surface of the wood powder particles 121 of the wood powder 120.

When a plastic board was formed by using the wood powder 120 obtained in this way as a pigment, a white board with no color unevenness could be obtained. Further, this board had a good feel to the touch, no sticky feeling, and little expansion and contraction due to temperature change.

Incidentally, this is the wood powder grain 11 which is the carrier base material.
1,121 and the state in which the pigment particles as the surface grains 112,122 intrude into the surface portion of the crushed wood powder 102 to be treated are more favorable results by imparting a stronger mechanical impact during the milling treatment. Cause For example, in addition to each of the experimental examples described above, a ball mill having an agitating blade in the vertical direction is used, and the crushed wood powder 102 and the wood powder particles 111 and the surface particles 112 and 122 of the pigment particles are ground and dropped. When they were bite-bonded under the conditions of, the wood powders 110 and 120 having a more vivid color could be obtained.

[Wood flour having conductive fine powder particles] Next, as the surface grains 112 and 122, the conductive fine powder particles are fixed to the surface portions of the wood flour grains 111 and 121, respectively.
I will describe.

As described above, the conductive fine powder particles used for the surface particles 112 and 122 are higher in hardness than the wood powder particles 111 and 121 and the crushed wood powder 102 to be treated. It has hardness and the wood powder grains 111, 12
1 and the specific condition that the particle size of the processed crushed wood powder 102 is relatively small corresponding to the particle size of the crushed wood powder 102, and it is necessary to consider the use condition in the object to be mixed, such as heat resistance. Fine powder particles having arbitrary conductivity can be used.

Examples of such conductive fine powder particles include fine powder particles of conductive metal such as Ag, Cu and Ni, and Sn.
There are fine particles of conductive metal oxides such as O ₂ and ZnO, and fine particles of carbon-based conductive particles, and one or more of these may be selectively used.

Then, the surface grains 11 and 121 and the surface portion of the crushed wood powder 102 to be treated are treated with the surface grains 11
The wood powders 110 and 120, in which the conductive fine powder particles are embedded and bonded as 2,122, are conductive fillers for the paint,
For example, it can be used as an electromagnetic wave shielding material, an electromagnetic wave absorbing material, an antistatic material, etc. by being mixed and dispersed in a coating liquid such as various resin paints.

Next, the particle diameters of the wood powder particles 111 and the wood powder particles 121 (in this case, the crushed wood powder to be treated 102) supporting the conductive fine powder particles as the surface particles 112 and 122 are as small as possible. It is desirable that they are arranged in a very fine particle size range.

[0205] For example, wood flour grain 111 and second wood flour 120
Then, it is preferable that the main part of the crushed wood powder to be treated 102 has a particle size distribution included in the particle diameter range of 2 to 12 μm. In addition, the other one of the preferable particle size distribution is wood powder grain 1
11. In the second wood powder 120, the crushed wood powder 102 to be processed is 3
It is preferable that the particles have a particle size of 2 μm or less. Further, it is more preferable that the particles have a particle size of 20 μm or less. Still another effective particle size distribution is that particles having a particle size of 12 μm or less occupy 75 wt% or more, preferably 80 wt% or more of the total amount.

Further, the surface grains 112, 12 of the wood powder grains 111, 121 and the surface portions of the crushed wood powder 102 to be treated are treated.
The means for supporting the conductive fine powder particles as 2 may be the same as in each of the above-mentioned examples, and the conductive fine powder particles are the surface portions of the wood powder grains 111 and 121 as the carrier base material. It is preferable that the wood powder 110 and 120 carrying the conductive fine powder particles thus obtained has good fluidity,
It was confirmed to have dispersibility.

Further, the amount of the conductive fine powder particles carried on the wood flour particles 111 and 121 may be any amount as long as it satisfies various required electric conductivities, and basically, the carried conductive fine powder particles are provided. Are required to have an electrical connection relationship with each other, and the supported amount is increased until the conductivity is satisfied.

Then, surface grains 112, 122 are formed on the surface portions of the wood flour grains 111, 121 and the crushed wood flour 102 to be treated.
Of the conductive fine powder particles as a solid wood powder 110, 12
An experimental example and a comparative example in each processing operation for obtaining 0 will be specifically described. (It should be noted that, for better understanding of this experimental example, for the objects having the same contents as those in the above-mentioned example, for example, the raw wood 101, the crushed wood powder 1 to be treated 1
02, wood flour grains 111 and 121, and wood flour 110 and 120 will be assigned the same numbers for the description. )

Experimental Example D-1. Ezo pine sawdust having the particle size distribution shown in Table 1 above, in this case, raw wood 10 as a raw material
Regarding No. 1, by using an impeller mill (IMP-250 manufactured by Seishin Enterprise Co., Ltd.), the clearance between the impact blade of the crushing rotor rotating at high speed and the liner was set to 3 mm, and the impact, shearing, grinding, etc. The crushing process was performed by crushing, and the unprocessed crushed wood powder 102 shown in Table 2 was obtained.

The crushed wood powder 102 thus treated was classified to obtain the crushed wood powder 102 having the particle size distribution shown in Table 3, and then the classified crushed wood powder 102 was further treated. Similarly for the crushed wood flour 102, the diameter is 3 mm.
Using a 5.4 liter capacity dry type ball mill (Mitsui Miike Kakoki Co., Ltd. Attritor A-200) loaded with 2.4 liters of zirconia-based ceramics crushed balls, this was milled for 2 hours, Wood flour grains 111 having the bulk specific gravity and the grain size distribution shown in Table 4 were obtained.

Further, the wood powder grain 111 thus obtained
On the other hand, carbon fine particles as conductive fine particles depending on the amount to the extent that the surface part is hidden, in this experimental example, 1
50 parts by weight of fine carbon powder particles are added to 00 parts by weight of fine wood particles 111 and sprinkled, and then fine carbon particles are fixed on the surface part by using the same ball mill as described above.
I got 0.

Subsequently, 20 parts by weight of a urethane resin was added to 60 parts by weight of a solvent in which dimethylformamide and methyl ethyl ketone were mixed in a ratio of 1: 1 to prepare a coating solution. Wood powder 11 having resin solids and the carbon fine particles supported on the surface
0 and 1 were mixed at a weight ratio of 1: 1 and then kneaded for about 10 minutes using a ball mill to obtain a conductive coating material.

A coating film having a thickness of about 21 μm was formed using the conductive coating material obtained in this step, and the electric resistance value of the surface was measured. The value was 1 × 10 ⁷ Ω to 1 × 10 ⁸ Ω. It was confirmed that good conductivity was brought about.

[0214] Further, the urethane resin solid content in the coating liquid and the wood powder 11 having the carbon fine powder particles carried on the surface portion thereof.
And 0 were mixed in a weight ratio of 1: 2, and then kneaded for about 10 minutes to obtain a conductive paint.

A film thickness of 2 is obtained by using the conductive paint obtained here.
When a coating film having a thickness of about 8 μm was formed and the electric resistance value of the surface thereof was measured, it was confirmed that the film had better conductivity than the coating film using the above-mentioned conductive paint.

Experimental Example D-2. The raw material wood 101 was crushed by the same method as in Experimental Example D-1 to obtain the treated pulverized wood powder 102 having the particle size distribution shown in Table 2, which was then classified and treated with the particle size distribution shown in Table 3 above. Crushed wood flour 102 was obtained. 2 kg of the crushed wood powder 102 to be treated and 1 kg of carbon fine powder particles used as the surface particles 122 were prepared, and the carbon fine powder particles were sprinkled on the crushed wood powder 102 to be treated.
This crushed wood powder 102 to be treated sprinkled with carbon fine particles
Was ground with a dry ball mill (Attritor A200 manufactured by Mitsui Miike Kakoki Co., Ltd.) for 2 hours to give 12 pieces of wood flour.
I got 0.

It was confirmed that the surface of the wood powder 120 obtained in this manner was adjusted and the bulk specific gravity was increased, and that the fine carbon powder particles were fixed to the surface portion in a bite state.

[0218] A coating film was formed from the paint using the wood powder 120 obtained in this step as a filler, and the electric resistance value of this coating film was measured. Was given.

Comparative Example D-1 To 100 parts by weight of a urethane resin solution having a concentration of 1.30%, 30 parts by weight of carbon fine particles were added, and then kneaded for about 10 minutes using a ball mill to give a conductive coating. Obtained.

Then, a coating film having a film thickness of about 21 μm was formed using the conductive coating material obtained in this step, and the electric resistance value of the surface was measured.
A value of ⁰⁹ Ω was shown, and it was confirmed that carbon was agglomerated in the coating film.

Next, the urethane resin solution and the carbon fine particles are continuously kneaded so that the surface electric resistance value at the time of forming the coating film becomes 1 × 10 ⁸ Ω or less, and at each set kneading time. The surface electric resistance value as a coating film was measured, and when the kneading was performed for 40 to 50 hours by continuous kneading using a ball mill, the surface electric resistance value of the formed coating film surface was 1 × 10 ^{8 for the first time.} Ω was confirmed.

Comparative Example D-2. The raw material wood 101 was crushed by the same method as in Experimental Example D-1 to obtain the crushed wood powder 102 to be processed having the particle size distribution shown in Table 2, which was then classified and crushed to be processed having the particle size distribution shown in Table 3. Wood flour 102 was obtained. Further, 2.4 liters of the crushed wood powder 102 to be treated was loaded with 2.4 liters of zirconia-based ceramic crushing balls having a diameter of 3 mm.
Using a dry ball mill with a capacity of 4 liters (Attritor A-200 manufactured by Mitsui Miike Kakoki Co., Ltd.), this was ground for 2 hours to obtain wood powder grains 111 of the particle size distribution shown in Table 4 above.

Then, using a solvent in which dimethylformamide and methyl ethyl ketone were mixed in a ratio of 1: 1,
After blending with a 25% strength urethane resin solution diluted with this solvent, the wood powder particles 111; carbon fine powder particles; the solid content ratio of the urethane resin solution is 2: 1: 3 Using a ball mill, the mixture was kneaded for about 10 minutes to obtain a conductive paint.

Then, using this conductive paint, a film thickness of 21 is obtained.
When a coating film of about μm was formed and the electric resistance value of the surface was measured, it showed a value of 1 × 10 ⁹ Ω on any surface portion of the coating film, and that carbon was agglomerated in the coating film. Was confirmed.

Then, the kneading of these urethane resin solutions with the wood powder particles 111 and the fine carbon powder particles is continued so that the surface electric resistance value at the time of forming the coating film becomes 1 × 10 ⁸ Ω or less. At the same time, the surface electric resistance value as a coating film was measured at each set kneading time, and when the kneading was performed for about 40 hours by continuous kneading using a ball mill, the surface electric resistance value was 1 × 10 ⁸ for the first time. Ω was confirmed.

Comparative Example D-3. The wood powder grains 111, the carbon fine powder grains, and the urethane resin solid content in Comparative Example D-2 were blended in a weight ratio of 4: 2: 3,
A conductive coating material was obtained under the same conditions as in Comparative Example D-2 except for this, and then a coating film having a film thickness of about 28 μm was formed using this conductive coating material, and the electric resistance value of the surface was adjusted. When measured, 1 × 10 ⁹ Ω on any surface of the coating film
It was confirmed that carbon was agglomerated in the coating film.

[Wood flour having surface grains other than the above and wood grains having surface grains having different properties] In the above embodiment, the wood flour grains 111 and 121 and the crushed wood flour 102 to be treated are fixed. It is clarified that an inorganic material, a pigment, a conductive material, and a metal material are conveniently used as the surface grains 112 and 122.

As is clear from the above description of the embodiment, the present invention includes the use of particles made of a material other than the inorganic material, the pigment, the conductive material and the metal material as the surface particles 112 and 122.

That is, the wood powder grains 111 having an increased bulk specific gravity,
If the particles are smaller and harder than 121 and the crushed wood powder 102 to be treated, for example, various plastic particles and the like can be used in the wood powder grain 111 or the second wood powder 120 as in the above embodiment. It is used as the surface grains 112 and 122 fixed to either the treated ground wood flour 102 or the wood flour grain 121.

[0230] Further, the obtained wood powders 110 and 120 may have a composite function, such as conductivity and coloring, at the same time. In this case, the pigment and the conductive material are used as one wood powder grain 11
By immobilizing it on the surface of Nos. 1 and 121, the wood flours 110 and 120 having both a conductive function and a coloring function can be obtained.

When the wood flours 110 and 120 having such a composite function are obtained, various functions required for the wood flours 110 and 120 are applied to plastic products obtained by using the wood flours 110 and 120. A plurality of types of surface grains 112 each having such a function in order to effectively bring them,
122 is prepared and the required function is wood flour 11
1 grain of wood flour with a blending ratio that effectively produces 0 to 120
11, 121 and crushed wood powder 102 to be treated are used by fixing.

[0232] The wood flours 110 and 120 thus obtained are
It can be used as a filler for various plastic products, can be added to paints, etc., and can also be used for various purposes such as pressing wood powders 110 and 120 to form boards. ..

[0233]

As is apparent from the above examples, according to the present invention, the crushed wood powder to be treated is crushed by friction between the crushing balls to thereby crush the crushed wood to be treated. It is obtained by removing the angular, protruding, and cilia-like whisker parts of the powder, and increasing the bulk specific gravity of the powder, which has various surface grains. Both the first wood powder 110 and the second wood powder 120 have good fluidity and good dispersibility in a solvent or the like.

Further, the surface grains can be uniformly and easily fixed to the surface portion of the crushed wood powder to be treated or the surface portions of the wood powder grains, and the surface grains can be thermally and chemically It is stably immobilized on the surface of the pulverized wood powder or wood powder particles to be treated.

Further, since the surface portion of the formed wood powder is covered with the surface grains, various characteristics and various properties of the wood material to be treated or the wood material having the wood powder grains forming the wood powder are obtained. The function is effectively protected by the surface grains.

[0236] Further, surface particles which retain various characteristics and functions of the raw material wood and have various functions on the surface, for example, one of fine powder particles such as pigment, conductive material, inorganic material, metal material, plastic material or the like. Providing the properties and functions of the raw wood and the properties and functions of the surface grains fixed to the surface part to the object to be used, by using two or more types of fixed wood flour You can

Further, by immobilizing the surface grains having a relatively fine particle diameter on the surface portion of the crushed wood powder or the wood powder grains to be treated, it is possible to prevent agglomeration between the surface grains and at the same time It is possible to more effectively bring the various characteristics and functions that it has to the object to be used.

By immobilizing the surface grains having a relatively fine particle size on the surface portion of the crushed wood flour or the wood grain to be treated, the grains having a diameter much larger than the individual surface grains, Moreover, since the particles have the same functions and characteristics as the surface particles, the characteristics and functions of the surface particles can be more remarkably brought to the object to be used, and the particles can be used without being relatively precipitated in the coating liquid. be able to.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a process of forming a crushed wood powder to be processed from a raw material wood and immobilizing a plurality of surface grains on a surface portion of the crushed wood powder to be processed according to an embodiment of the present invention; It is a schematic explanatory drawing which showed typically each process of the formation of the wood powder grain from wood powder, and the fixation of each surface grain of the several surface grain part of the said wood powder grain.

FIG. 2 is a vertical sectional front view of essential parts showing an outline configuration of an open type dry ball mill according to an example for performing a grinding process by a frictional action on a ground wood powder and a wood powder grain to be processed.

FIG. 3 is a longitudinal sectional front view of a main part showing a schematic configuration of a sealed dry ball mill according to an example for performing a grinding process by a frictional action on a ground wood powder and a wood powder grain to be processed.

FIG. 4 is a longitudinal sectional front view of a main part showing a schematic configuration of a classifying device according to an example for classifying the crushed wood powder and the wood powder particles.

[Explanation of symbols]

 101 Raw Wood 102 Milled Wood Powder to Be Treated 110 First Wood Flour 111 Wood Flour Grain 112 Surface Grain 120 Second Wood Flour 121 Wood Flour Grain 122 Surface Grain 1 Mill Main Body 2 Cooling Jacket 3 Grinding Ball 4 Stir Bar 5 Motor 6 Removal valve 7 Removal port 8 Water supply pipe 9 Drain pipe 10 Sealing lid 11 Exhaust pipe 12 Air supply pipe 13 Classification rotor 14 Motor

Continuation of the front page (31) Priority claim number Japanese Patent Application No. 3-208929 (32) Priority date Hei 3 (1991) July 26 (33) Priority claiming country Japan (JP) (31) Priority claim number Special Japanese Patent Application No. 3-307132 (32) Priority Day No. 3 (1991) October 28 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 3-321567 (32) Priority Day No. 3 (1991) October 31 (33) Priority claiming country Japan (JP) (31) Priority claim number Japanese Patent Application No. 3-321579 (32) Priority Date Hei 3 (1991) October 31 (33) Priority Claiming country Japan (JP)

Claims (30)

[Claims] 1. A pulverized wood powder to be treated obtained by pulverizing raw wood is pulverized by a frictional action between pulverizing balls,
The wood powder particles have an increased bulk specific gravity, and a plurality of surface particles smaller and harder than the wood powder particles are fixed to the surface portion of the wood powder particles having an increased bulk specific gravity by pressing external force. Wood flour characterized by being characterized. 2. The immobilization of a plurality of surface particles against the surface portion of the wood powder particles having an increased bulk specific gravity by pressing external force,
The wood flour according to claim 1, wherein the wood powder is mainly a bite bond of a plurality of surface grains to the surface portion. 3. Immobilization of a plurality of surface grains against the surface portion of the wood powder grain having an increased bulk specific gravity by pressing external force includes embedding of the plurality of surface grains into the surface portion. Bond, or sandwiching bond between a plurality of surface grains bite-bonded to the surface part, or one or more surface grains bite-bonded to the surface part, and hugging bond to each surface part At least one of the interlocking bonds with one another with one or more surface grains
The wood flour according to claim 1, wherein the wood flour is three or more. 4. The wood flour according to claim 1, wherein the plurality of surface grains that are smaller and harder than the wood flour grains having an increased bulk specific gravity are mainly pigments. 5. The wood flour according to claim 1, wherein the plurality of surface grains that are smaller and harder than the wood grain grains having an increased bulk specific gravity are mainly conductive materials. 6. The plurality of surface particles, which are smaller and harder than the wood powder particles having an increased bulk specific gravity, are any one of an inorganic material, a metal material, and a plastic material. Wood flour. 7. A plurality of surface particles, which are smaller and harder than the wood powder particles having an increased bulk specific gravity, are pigments, conductive materials, inorganic materials,
The wood flour according to claim 1, which is two or more kinds selected from metal materials and plastic materials. 8. A crushed wood powder to be processed obtained by crushing raw wood is crushed by friction between crushing balls,
While being made into wood flour particles having an increased bulk specific gravity, the above-mentioned pulverization to be processed is applied to the surface portion of the pulverized wood powder having the increased bulk specific gravity or the surface portion of the wood powder particles having an increased bulk specific gravity. Wood flour characterized in that a plurality of surface grains that are smaller and harder than wood flour and wood grains with an increased bulk specific gravity are fixed by pressing external force. 9. Immobilization of a plurality of surface grains against the surface portion of the crushed wood powder to be treated or the surface portion of the wood powder grain having an increased bulk specific gravity by an external force mainly applies the plurality of surfaces to the surface portion. The wood flour according to claim 8, wherein the wood flour is a bite bond. 10. Immobilization of a plurality of surface grains against the surface portion of the crushed wood powder to be treated or the surface portion of the wood grain particles having an increased bulk specific gravity by an external force presses the plurality of surface grains to the surface portion. Hugging bond by the surface part including the biting of, or sandwiching bond by a plurality of surface particles bite-bonded to the surface part, or one or more surface particles biting-bonded by the surface part 9. The wood flour according to claim 8, wherein the wood flour has at least one interlocking bond with each other and one or more surface grains huggingly bonded to the surface portion. 11. The wood flour according to claim 8, wherein the crushed wood flour to be treated and the surface grains smaller and harder than the wood grain grains having an increased bulk specific gravity are mainly pigments. 12. The wood powder according to claim 8, wherein the surface ground particles smaller and harder than the ground wood powder to be treated and the wood powder particles having an increased bulk specific gravity are mainly conductive materials. 13. A surface grain which is smaller and harder than the crushed wood powder to be treated and the wood powder grain having an increased bulk specific gravity is one of an inorganic material, a metal material and a plastic material. Item 8. The wood flour according to item 8. 14. The crushed wood powder to be treated and the surface particles smaller and harder than the wood powder particles having an increased bulk specific gravity are pigments,
The wood flour according to claim 8, which is at least two kinds selected from a conductive material, an inorganic material, a metal material, and a plastic material. 15. A pulverized wood powder to be treated obtained by pulverizing raw wood is pulverized by a frictional action between pulverizing balls to obtain a pulverized wood powder having a high bulk specific gravity. A step of forming, a step of preparing a plurality of surface particles that are smaller and harder than the wood powder particles, the surface portion of the wood powder particles having an increased bulk specific gravity, the plurality of surface particles by pressing external force. And a step of immobilizing the wood powder. 16. The immobilization by a pressing external force of a plurality of surface grains against the surface portion of the wood powder grains having an increased bulk specific gravity is mainly a bite bond of the plurality of surface grains to the surface portion. The method for producing wood flour according to claim 15. 17. Immobilization of a plurality of surface grains against the surface portion of the wood powder grain having an increased bulk specific gravity by an external force pressing against the surface portion includes embedding of the plurality of surface grains into the surface portion. Incorporation bond, or sandwiching bond of a plurality of surface grains that are bite-bonded to the surface part, or one or more surface grains that are bite-bonded to the surface part, and hugging bond to the surface part The method for producing wood flour according to claim 15, wherein the method comprises at least one or more sandwiching bonds with one or more surface grains. 18. The method for producing wood flour according to claim 15, wherein the plurality of surface grains that are smaller and harder than the wood flour grains having an increased bulk specific gravity are mainly pigments. 19. The method for producing wood powder according to claim 15, wherein the plurality of surface particles smaller and harder than the wood powder particles having an increased bulk specific gravity are mainly conductive materials. 20. The plurality of surface particles, which are smaller and harder than the wood powder particles having an increased bulk specific gravity, are any one of an inorganic material, a metal material, and a plastic material.
The method for producing wood flour according to 1. 21. The plurality of surface particles smaller and harder than the wood powder particles having an increased bulk specific gravity are two or more kinds selected from pigments, conductive materials, inorganic materials, metal materials and plastic materials. The method for producing wood flour according to claim 15, which is characterized in that. 22. A step of preparing a crushed wood powder to be treated obtained by crushing a raw material wood and a plurality of surface grains smaller and harder than this, and these crushed wood powder to be treated and a plurality of surface grains. Of the crushed wood powder to be crushed by the frictional action between the crushing balls to form wood powder particles having an increased bulk specific gravity. Part, or the surface part of the wood flour grain having an increased bulk specific gravity, and the step of immobilizing the other plurality of surface grain by pressing external force, at least. 23. The crushed wood powder to be treated and a plurality of surface grains are supplied in a state in which a plurality of surface grains are sprinkled on and adhered to the crushed wood powder to be treated. Item 23. A method for producing wood flour according to Item 22. 24. The method for producing wood flour according to claim 22, wherein the crushed wood flour to be treated and a plurality of surface grains are individually and separately supplied at the same time. 25. Immobilization of a plurality of surface grains against the surface portion of the crushed wood powder to be treated or the surface portion of the wood powder grain having an increased bulk specific gravity by an external force mainly applies the plurality of surfaces to the surface portion. 23. The method for producing wood flour according to claim 22, wherein the binding is by biting of grains. 26. Immobilization of a plurality of surface grains against the surface portion of the crushed wood powder to be treated or the surface portion of the wood powder grains having an increased bulk specific gravity by an external force causes the plurality of surface grains to be fixed to the surface portion. A hugging bond by the surface part including the bite of the above, a sandwiching bond by a plurality of surface particles bite-bonded to the surface part, or one or more surface particles bite-bonded by the surface part. 23. The method for producing wood flour according to claim 22, characterized in that at least one or more of sandwiching bonds with each other with one or more surface grains hugged and bonded to the surface portion. 27. The production of wood flour according to claim 22, characterized in that the surface ground particles smaller and harder than the ground wood flour to be treated and the wood flour particles having an increased bulk specific gravity are mainly pigments. Method. 28. The wood powder according to claim 22, wherein the surface ground particles smaller and harder than the ground wood powder to be treated and the wood powder particles having an increased bulk specific gravity are mainly conductive materials. Production method. 29. The surface grain which is smaller and harder than the crushed wood powder to be treated and the wood powder particle having an increased bulk specific gravity is any one of an inorganic material, a metal material and a plastic material. Item 23. A method for producing wood flour according to Item 22. 30. The crushed wood powder to be treated and the surface particles smaller and harder than the wood powder particles having an increased bulk specific gravity are pigments,
23. The method for producing wood flour according to claim 22, wherein the wood powder is at least two selected from a conductive material, an inorganic material, a metal material, and a plastic material.