JP2009113364A - Compression-formed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a board using the husks of agricultural products as natural stocks while suppressing bending strength and warpage. <P>SOLUTION: The compression-formed board 1 includes the husks of agricultural products, and includes: a base material 2 formed in such a manner that the husks subjected to pulverization are heated and compressed together with an adhesive; a surface layer(s) 3 provided at either or both of the surface and back face of the base material 2. Then, the surface layer(s) 3 has translucency to a degree at which the husks can be visually recognized. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a compression molded board containing a crop shell such as rice husk.

  As boards for furniture and building materials, boats (particle boards, etc.) that have been conventionally formed by mixing small pieces of natural materials such as wood chips and agricultural products with adhesives and heating and compressing them have been proposed in various forms ( Patent Document 1 and others). Such a board made of natural materials is also recommended from the viewpoint of utilization of waste and environmental protection (utilization of biomass material).

  In a board formed by compression-molding small pieces of natural material, the surface smoothness is lowered by forming a large number of concave portions due to gaps between the small pieces on the surface. It is known that the surface is polished or covered with a decorative paper to improve smoothness.

Conventionally, the particle board has a multi-layer structure, and the upper and lower layers, which are the surface layer, are made dense by compressing with fine pieces (chips) in the upper and lower layers than the center layer, and the entire board is smooth. It is also known to increase the property and bending strength and to suppress the overall warpage (Patent Document 2).
JP 2000-37712 A Japanese Patent Laid-Open No. 6-166011

  However, when wood chips and sawdust etc. are used as wood chip contained in the particle board, it is often not stored in a well-controlled state before being used for the board (similar to open field) Therefore, it contains a lot of moisture. When a board is formed by compression molding a small piece of natural material, there is a problem that depending on the type of adhesive, moisture contained in the material hinders the reaction. Therefore, there is a case where a step of drying the wood chip is purposely added for forming the board.

  On the other hand, crops, especially grains such as fir and wheat, are threshed after being stored in a storage in a dry state, and thus have an advantage that they are easily available in a dry state.

  Accordingly, the present invention solves the above-described problems, and pays attention to the crop shell, and practically finishes the board using the crop shell at a low cost while suppressing bending strength and warpage. Is an issue.

  To achieve the above object, the compression molded board according to claim 1 is a compression molded board containing a crop shell, wherein the first layer is made of the crop shell, and the crop shell is made. And a second layer stacked on top and bottom so as to sandwich the first layer, and the first and second layers are layers in which an isocyanate-based adhesive is mixed. The second layer has a higher blending ratio of the adhesive than the first layer, and the second layer is compressed more densely than the first layer. is there.

  The compression molded board according to the invention of claim 2 is a compression molded board containing a crop shell, wherein the first layer is made of the crop shell and the crop shell is the first layer. A second layer that is laminated vertically so as to sandwich the layer of the first layer, the material of the first layer is a shell of the crop that has been crushed to a predetermined size, The raw material is a fine powder of the shell that is generated as a result of pulverization of the crop shell used in the first layer, and the second layer is compressed more densely than the first layer. It is characterized by this.

  The invention according to claim 3 is the compression molding board according to claim 2, wherein the first and second layers are blended with an isocyanate-based adhesive, and the second layer is The blending ratio of the adhesive is higher than that of the first layer.

  According to the first aspect of the present invention, the first layer and the second layer sandwiching the upper and lower sides thereof are made of a crop shell in which an isocyanate adhesive is blended. Isocyanate-based adhesives cure by reacting with moisture contained in the shell and air, or the OH groups of cellulose contained in the shell, but generate heat as the curing occurs. The higher the blending ratio of the system adhesive, the higher. Therefore, during compression molding, the internal temperature of the second layer is higher than that of the first layer, quickly reaches the temperature at which the shell plasticizes (softens), and the second layer has a higher temperature than the first layer. Therefore, the second layer can be more densely formed than the first layer. Since the second layer sandwiching the upper and lower sides of the first layer is densely formed, warpage is suppressed as a whole, and bending strength is increased. Furthermore, since the isocyanate-based adhesive is cured by reacting with moisture, it is possible to relax the drying conditions of the shell before the reaction.

  According to the invention described in claim 2, the first layer and the second layer sandwiching the upper and lower sides thereof are all made of a crop shell, but the first layer has a predetermined size for the shell. The second layer is a fine powder (sieving powder) of the shell that is generated as a result of pulverization of the shell. That is, since the material of the second layer uses a much finer shell material than the material of the first layer, it is easy to be compressed at a high density when compression molding. The second layer can be formed more densely than the layer. Since the second layer sandwiching the upper and lower sides of the first layer is densely formed, warpage is suppressed as a whole, and bending strength is increased.

  In addition, the fine powder of the shell used for the second layer is originally discarded as garbage generated along with the crushing of the shell, but since this is utilized for the second layer, Providing environmentally friendly boards that eliminate the waste of raw materials during manufacturing.

  According to the third aspect of the present invention, the first and second layers are blended with an isocyanate-based adhesive, and the blending ratio of the second layer is higher. Isocyanate-based adhesives cure by reacting with moisture contained in the shell and air, or the OH groups of cellulose contained in the shell. The higher the blending ratio of the system adhesive, the higher. Therefore, during compression molding, the internal temperature of the second layer is higher than that of the first layer, quickly reaches the temperature at which the shell plasticizes (softens), and the second layer has a higher temperature than the first layer. It is easier to compress with higher density. Accordingly, the second layer can be formed more densely than the first layer in combination with the second layer using a finer material than the first layer. And since the 2nd layer which pinches | interposes the upper and lower sides of the 1st layer is formed densely, curvature as a whole is suppressed and bending strength is also raised. Furthermore, since the isocyanate-based adhesive is cured by reacting with moisture, it is possible to relax the drying conditions of the shell before the reaction.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The compression-molded board 1 of the present invention is a board containing a crop shell, and as the crop, a grain is suitable, and rice, barley, wheat, buckwheat, awa, koe, acne, corn, beans, etc. can be used. . In particular, rice husk, which is a rice husk, is easily available in large quantities compared to other materials and can be used as an industrially stable material. Therefore, in the following description, the compression molding board 1 using rice husk as a shell for agricultural products will be described.

  Rice husks have a bulk specific gravity as small as about 0.15 to 0.2 when they are separated from rice, so that the rice husks pulverized to have a bulk specific gravity of about 0.8 (hereinafter simply referred to as rice husks) 13) is used. In this case, it is preferable to grind in the direction in which the fiber structure of the rice husk remains long.

  As shown in FIG. 1A, the compression-molded board 1 has a three-layer structure, and a first first layer 11 in the center and a second layer 12 stacked on the upper and lower sides sandwiching the first layer 11 respectively. In any case, the rice husk 13 is mixed with an isocyanate adhesive 15. The second layer 12 as the surface layer is compression-molded so as to be denser (higher density) than the first layer 11. In this way, by finishing the second layer 12 as a surface layer densely, the bending strength of the entire compression molded board 1 can be increased and warpage can be suppressed, and the smoothness of the second layer 12 is increased. Even if the decorative paper is pasted thereon, the unevenness of the second layer 12 (compression-molded board 1) is hardly affected by the decorative paper.

  Next, the manufacturing method of the compression molding board 1 of 1st Embodiment is demonstrated. As a material for the first layer 11, a material in which M2% of an uncured isocyanate-based adhesive 15 is mixed with the rice husk 13 is prepared in advance, and an uncured material for the rice husk 13 is prepared as the material for the second layer 12. A material prepared by blending isocyanate adhesive 15 with M1%, which is greater than M2%, is prepared. That is, the blending ratio of the adhesive 15 with respect to the rice husk 13 is set to be higher in the second layer 12 than in the first layer 11.

  The mixing ratios M1 and M2 are preferably set in the range of 5 to 20%. Here, as an example, M1 is set to 15% and M2 is set to 5%. As the isocyanate-based adhesive, the product name “B1601” manufactured by Oshiya Resin is suitable.

And as shown in FIG.1 (b), the 2nd layer 12 which mix | blended the uncured isocyanate type adhesive 15 with the chaff 13 also in the inside of the frame 2 used for a hot press apparatus on the conditions mentioned above. The material of the first layer 11, the material of the first layer 11, and the material of the second layer 12 are sequentially added in layers, and are pressurized for a predetermined time while heating. The molding conditions are preferably selected from the range where the heating temperature is 140 to 180 ° C., the pressure is the range of 15 to 50 kg / cm ² , and the heating time is 20 to 40 minutes.

  When pressed under the above conditions, the uncured isocyanate-based adhesive 15 blended in the rice husk 13 is bonded to urea in the air or reacts with moisture adhering to the rice husk 13, or to the rice husk 13. It hardens | cures with heat_generation | fever by one or both of the urethane bond which reacts with the OH group of the contained cellulose. Although the curing reaction of the isocyanate-based adhesive 15 is an exothermic reaction, as shown in FIG. 2, the reaction proceeds rapidly when the blending ratio of the adhesive is high, so that the temperature at which the chaff 13 is plasticized (about 200 ° C. ) Is reached in a shorter time as the blending ratio is higher.

  Therefore, since the uncured isocyanate-based adhesive 15 is contained in the second layer 12 at a higher blending ratio than the first layer 11, the second layer 12 is harder than the first layer 11 when cured. The internal temperature of the layer 12 rapidly increases (becomes higher than the external temperature, which is the molding temperature), and plasticization (softening) proceeds rapidly. Therefore, when the pressure is applied in this state, the second layer 12 is easily crushed so that it is easily compressed to a high density, and the first layer 11 is sandwiched between the denser second layers 12. The compression molding board 1 can be easily formed.

  Moreover, since the isocyanate-type adhesive 15 applied to the compression molding board 1 of the present invention reacts with moisture as described above and cures, the drying conditions of the rice husk 13 that is the material can be relaxed. That is, it is not necessary to add a step of drying the chaff 13 in order to increase the reactivity with the adhesive.

  In addition, since the isocyanate-based adhesive 15 does not generate formaldehyde, which is a major cause of sick house syndrome, the compression molded board 1 of the present invention can be used for furniture and building materials as a human-friendly board. Furthermore, since the isocyanate-based adhesive 15 contains a nitrogen component, if the compression molded board 1 is disposed in the soil when the compression molded board 1 is discarded, the nitrogen component acts as a fertilizer, so there is no fear of polluting the environment.

  As a modification of the above embodiment, a hot press apparatus having a structure in which steam is sprayed onto the second layer 12 at the time of compression molding is adopted, and the rice husk 13 included in the second layer 12 is formed by steam. It may be rapidly plasticized at a high temperature. However, this method complicates the structure of the hot press device and causes an increase in cost. As described above, it is more costly to change the blending ratio of the adhesive so as to use the exothermic reaction at the time of curing. But it is beneficial.

  Next, the compression molding board 1 of 2nd Embodiment is demonstrated. Although the compression molding board 1 of 2nd Embodiment is not shown in figure, it replaces with the 2nd layer 12 instead of the crushed rice hull 13, and when the rice hull 13 is grind | pulverized to a predetermined | prescribed magnitude | size, it is secondary. The generated fine powder is used. The fine powder is a dust-like sieving powder and is the same component as the rice husk 13, but is originally discarded at the time of manufacture.

  As compared with the rice husk 13 of the first layer 11 obtained by pulverizing the fine powder 14 to a predetermined size, the fine powder of the second layer 12 is naturally very fine, so that it is crushed during compression molding. Therefore, the compression-molded board 1 having a three-layer structure in which the first layer 11 is sandwiched between the denser second layers 12 can be easily formed.

  In addition, because the fine powder that was originally disposed at the time of manufacture is effectively used for the compression-molded board 1, the waste of the rice husk in the production is reduced to zero. In combination, the compression-molded board 1 that is more environmentally friendly can be provided.

  Of course, as the third embodiment, the first embodiment and the second embodiment are combined, the fine powder of rice husk is used for the second layer 12, and the blending ratio of the isocyanate-based adhesive 15 is set to the first ratio. A configuration in which the second layer 12 is higher than the layer 11 may be employed.

(A) is a longitudinal cross-sectional view of the compression molding board of embodiment, (b) is a figure explaining the manufacturing method of a compression molding board. It is a figure which shows the relationship between the compounding rate of an isocyanate type adhesive agent, and a temperature rise.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compression molding board 2 Frame 11 1st layer 12 2nd layer 13 Rice husk 15 Adhesive

Claims (3)

A compression molded board containing crop shells,
A first layer made of a crop shell, and a second layer stacked up and down so as to sandwich the first layer using the crop shell,
Each of the first and second layers is a layer in which an isocyanate-based adhesive is mixed, and the second layer has a higher blending ratio of the adhesive than the first layer. The compression molded board is characterized in that the layer is compressed more densely than the first layer. A compression molded board containing crop shells,
A first layer made of a crop shell, and a second layer stacked up and down so as to sandwich the first layer using the crop shell,
The material of the first layer is the crop shell pulverized to a predetermined size, and the material of the second layer is secondary to the crop shell used for the first layer. And the second layer is compressed more densely than the first layer.   The first and second layers are blended with an isocyanate-based adhesive, and the second layer has a higher blending ratio of the adhesive than the first layer. Item 3. A compression-molded board according to Item 2.

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