JP2005319748A - Method for manufacturing woodmeal board and woodmeal board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily manufacture a plate-like woodmeal board in a satisfactory state without causing colapse of shape regardless of thickness. <P>SOLUTION: When the woodmeal board is molded by thermally pressing a formed mixture of woodmeal and a heat-curable resin, a porous material (nonwoven fabric) 6 is placed on a lower forming layer 5 and an upper forming layer 7 is formed on the porous material 6. Further, a forming mat 10 of a sandwich state formed as described is thermally pressed as it is into the woodmeal board 10a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a wood flour board obtained by hot pressing a mixture of wood flour and a thermosetting resin, and a wood flour board.

  It has been proposed to produce a wood flour board as a plate material by heat-pressing a mixture of wood flour and a thermosetting resin functioning as an adhesive. For wood flour as raw material, thinned wood, building waste, etc. are made into chips with known equipment, sander dust that is generated when sanding wood such as plywood and MDF, etc. is used, thermosetting resin As such, phenol resin, urea resin, isocyanate resin, epoxy resin, and the like are used.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-18207) describes a method for manufacturing such a wood flour board, and wood flour and thermosetting on a breathable sheet sent by a rotating belt. The mixture with the functional resin is formed into a mat shape and conveyed together with the sheet. In the middle, the forming mat is sucked from the back surface of the sheet and pre-pressed together with the sheet, and then hot-pressed.

  This is because pre-pressing is performed by removing air contained in the forming mat and stabilizing it. In the case of a forming mat in which fibers are intertwined, such as an MDF mat, the mat does not collapse even if air in the forming mat is ejected during hot pressure, but in the case of wood powder, Since there is no entanglement between the powders, the internal air is removed by pre-pressing to prevent the forming mat from collapsing or puncturing during hot pressing.

JP 2001-18207 A

  As described above, in the conventional method for producing a wood flour board, in order to obtain a high-quality plate-like wood flour board, a pre-press process for extracting air from the forming mat is required. For this reason, the equipment for performing the required suction and pressing is arranged in the manufacturing apparatus, and when the forming mat is thick, the existing air cannot be completely extracted, and the air remains. Can be sent to the hot-pressure stroke. In such a case, mat breakage tends to occur, so that many conventional wood flour boards are relatively thin.

  The present invention has been made in view of the circumstances as described above, and is capable of easily producing a plate-like wood flour board in a good state without losing its shape regardless of thickness and thickness. An object of the present invention is to provide a method for manufacturing a wood flour board and a wood flour board produced.

  In order to solve the above-mentioned problems, the present inventors intervened a porous material between the forming mats by carrying out an experiment in which a mixture of wood flour and a thermosetting resin is hot-pressed under various conditions. When the hot-pressing process is performed in a hot state, it has been found that even if the pre-pressing process as in the prior art is not performed, the shape is not deformed during the hot-pressing process. In addition, in the case of a thick wood flour board, it has been found that by interposing a plurality of porous layers, the shape deformation at the time of hot pressing does not occur even if the prepress process is not performed. The reason why the deformation does not occur is presumed that the air in the forming mat located above and below is extracted from the side of the mat (the end face) through the intervening porous layer during hot press. The

  The present invention is based on the above findings and is basically a method of forming a wood flour board by hot pressing a formed mixture of wood flour and a thermosetting resin, the formed mixture It is characterized in that a porous material is placed on the substrate and a mixture is further formed thereon at least once, and then the whole is hot-pressed.

  In the present invention, the porous material has heat resistance, and when the forming mat is hot-pressed, the air contained in the layer of the mixture of wood powder and thermosetting resin located above and below is porous. What is necessary is just to have the space | gap which can escape to the exterior through a material, and mesh-like things, such as a nonwoven fabric and cloth, Furthermore, a metal net, paper, etc. can be mentioned.

  In the present invention, the wood flour used in conventional wood flour boards can be used as it is. Examples include thinned wood and building waste made into chips with known devices, and sand dust produced when sanding wood such as plywood and MDF. There are no particular restrictions on the tree species. The particle diameter of the wood flour may be about 1 mm to 0.05 mm as in the conventional case.

  The thermosetting resin functions as an adhesive for wood powder, and examples thereof include phenol resin, melamine resin, urea resin, isocyanate resin, and epoxy resin. It can be a powder or a liquid. A phenol resin is particularly preferable because it is easy to mix the adhesive and the wood flour.

  In production, wood flour as a raw material is prepared by an appropriate method, and preferably dried to a moisture content of about 5%. A thermosetting resin as an adhesive is mixed with the dried wood powder by a method such as spray coating to obtain a mixture of the wood powder and the thermosetting resin. The mixing amount of the thermosetting resin is somewhat different depending on the type and the like, but is preferably about 10 to 30 wt% with respect to the total dry wood flour weight.

  For example, a predetermined amount of the obtained mixture is dispersed in a predetermined area of a lower heating plate of a hot-pressing device (forming) to form a lowermost forming mat. Preferably, the forming mat has a thickness of about 5 mm. A thin-film porous body is placed thereon, and a second-layer forming mat is formed thereon in the same manner. If the desired thickness is obtained, the hot pressing process is entered. In order to obtain a thicker wood flour board, the porous material is again placed on the second layer forming mat, and then the third layer forming mat is formed. Thereafter, the same procedure is repeated until the required thickness is reached, and then the hot pressing process is started.

  The thickness of the forming mat in each layer is preferably the same, but there is no problem even if it is different. Further, the thin film-like porous body is preferably made of the same material, but different materials can also be used. Further, a single thin film-like porous body may be placed on the forming mat, and depending on the thickness and material thereof, two or more laminated bodies may be placed on the forming mat.

The heat pressure may be the same as the heat pressure at the time of manufacturing the conventional wood flour board, and for example, the heat pressure is performed under conditions of 180 ° C., 3 minutes, 3 N / mm ^{2, and the} like. The wood flour board according to the present invention is completed by sanding the front and back surfaces of the wood flour board formed into a plate shape by hot pressure as necessary.

  As described above, according to the method of the present invention, a good wood flour board can be obtained even if the prepress step is omitted as in the conventional wood flour board manufacturing method. You may make it pre-press with respect to the forming mat which interposed the material as an intermediate | middle layer, and it may send in a hot-pressing process after that. The manufactured wood flour board has a porous material as an intermediate layer, and the physical properties are further stabilized.

  According to the present invention, a plate-like wood flour board can be easily manufactured in a good state without being deformed regardless of the thickness.

  Hereinafter, although an example explains the present invention, it is needless to say that the present invention is not limited to this example.

[Example 1]
Wood flour produced when cutting and sanding a softwood plywood was used as a raw material, and it was dried to a moisture content of 5%. A resol-type phenol resin was applied to the dried wood flour by spraying at a ratio of 20 wt% with respect to the total weight of the dried wood flour.

As shown in FIG. 1, the obtained mixture was sprayed on the lower heating platen 1 of the hot platen press until the thickness became 5 mm to form the lower forming layer 5. A non-woven fabric (weighing weight: about 300 g / m ² ) 6 made of polyethylene fibers was spread thereon, and the same mixture was sprayed thereon to a thickness of 5 mm to form an upper forming layer 7.

The upper heating plate 2 was pressed onto the forming mat 10 in a sandwich state, and hot pressed at 180 ° C. for 3 minutes at 3 N / mm ² . The hot press was opened, and a plate-shaped wood flour board (wood flour nonwoven fabric composite) 10a as shown in FIG.

  When the appearance of the obtained wood flour board was visually observed, it was not deformed and no cracks were observed.

[Example 2]
Wood flour produced when cutting and sanding the softwood plywood was used as a raw material, and it was dried to a moisture content of 5%. A novolac phenol resin (powder) was mixed with the dried wood flour at a ratio of 20 wt% with respect to the total dry wood flour weight. The resulting mixture was formed into a sandwich mat in the same manner as in Example 1.

The upper heating plate 2 was pressed on it, and hot pressed at 150 ° C. for 5 minutes at 3 N / mm ² . The hot press was opened, the plate-like wood flour board (wood flour nonwoven fabric composite) was taken out, and the front and back surfaces were sanded to a predetermined thickness.

  When the appearance of the obtained wood flour board was visually observed, it was not deformed and no cracks were observed.

[Comparative Example 1]
A wood flour board was formed in the same manner as in Example 1. However, laying the nonwoven fabric 6 between the lower forming layer 5 and the upper forming layer 7 was omitted. When the appearance of the obtained wood flour board was visually observed, voids and cracks were present in one board, and the quality was clearly inferior to the product of the example.

The figure explaining the manufacturing method of the wood flour board by this invention. The figure explaining the wood flour board by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Hot plate of hot press, 5 ... Lower forming layer, 6 ... Nonwoven fabric (porous body), 7 ... Upper forming layer, 10 ... Forming mat in a sandwich state, 10a ... Wood flour board

Claims (3)

  A method of forming a wood flour board by heat-pressing a foamed mixture of wood flour and thermosetting resin, placing a porous material on the formed mixture, and further mixing on the porous material A method for producing a wood flour board, wherein the entire body is hot-pressed after at least one step of forming the body.   The method for producing a wood flour board according to claim 1, wherein the porous material is a nonwoven fabric.   A wood flour board characterized in that at least one porous material layer is interposed as an intermediate layer in a mixture of heat-cured wood flour and a thermosetting resin.

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