JP4882280B2 - Wood board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a wooden board and a manufacturing method thereof, and more particularly to a wooden board having high bending strength and a manufacturing method of a wooden board with improved productivity.

  2. Description of the Related Art Conventionally, a wood board formed by using a formalin adhesive as an adhesive and heating and compressing a wood material is known.

For example, after making wood into small pieces (chips) as a raw material, a wooden board is added with a formalin-based adhesive, and the resulting mixture is formed (deposited) to form a mat. It is manufactured by a method of compression molding to a predetermined thickness under heating conditions.
JP 2002-18820 A

  However, the above-described method has a problem that the time for heat compression (press time at the time of hot-pressure molding) is long and the productivity of the wood board cannot be said to be sufficiently high.

  On the other hand, from the viewpoint of effective use of resources and resource recycling, the use of recycled materials is required as a raw material for wooden boards, and in order to reduce the amount of formaldehyde generated, the amount of formalin adhesive used is reduced. Is required. As a result, the bending strength of the wooden board is lowered, so that it is necessary to lengthen the press time at the time of hot pressing, and the productivity is lowered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wood board that exhibits high bending strength even if the pressing time during hot pressing is shortened.

  As a result of various studies, the present inventor has obtained the following knowledge. That is, when a wooden material is heated and compressed, if a compound having a boiling point of 120 ° C. to 400 ° C. is contained in the wooden material together with the formalin adhesive, the formalin adhesive can be used even if the pressing time during hot pressing is shortened. Surprisingly, it was found that the obtained wood board exhibits a high bending strength due to a synergistic effect with a compound having a boiling point of 120 ° C. to 400 ° C.

The present invention has been completed based on the above findings, and the first gist of the present invention is a wooden board obtained by heat compression of a wood material (excluding a piece of wood manufactured by a wood wool machine) (however, at the time of heat compression) In the case of a wood board comprising a compound having a boiling point of 120 ° C. to 400 ° C. (excluding polyethylene glycol) together with a formalin-based adhesive.

The second gist of the present invention is that a formalin-based adhesive and a compound having a boiling point of 120 ° C. to 400 ° C. (except for polyethylene glycol) are added to a woody material, and the resulting mixture is used on a cover paper. The present invention resides in a method for producing a wood board comprising heating and compressing.

  The wood board of the present invention exhibits high bending strength even when the pressing time at the time of hot pressing is short, and the manufacturing method is produced by shortening the pressing time at the time of hot pressing. Can be improved.

  Hereinafter, the present invention will be described in detail. The constituent elements described below are representative examples of the present invention, and the present invention is not limited to these contents.

  The wood board of the present invention is a molded body formed by heating and compressing a mixture of a wood material, a formalin adhesive and a compound having a boiling point of 120 ° C to 400 ° C.

  The wood material is not particularly limited, and examples thereof include new materials in which recycled materials are not mixed, mixed materials containing recycled materials, and the like. Recycled materials include building waste materials, plywood manufacturing factories, particle board manufacturing factories, MDF manufacturing factories, etc., wood recycling materials that use formalin-based adhesives such as plywood for formwork, and formalin-based adhesives. Examples include unused wood-recycled materials. These wood materials are generally used after being processed into particles for particle board or fibers for MDF.

  Formalin adhesives include resins obtained by the addition condensation reaction of compounds or phenols having amino groups in the molecule such as urea, thiourea, melamine, and benzoguanamine with formaldehyde, or co-condensation resins thereof. Can be used. As formaldehyde in the addition condensation reaction, formalin which is an aqueous formaldehyde solution is industrially used. These adhesives may be used in combination of two or more.

  The amount of the formalin-based adhesive in the woody board of the present invention is usually 2 to 25% by weight, preferably 3 to 20% by weight, more preferably 4 to 18% by weight. If it exceeds 25% by weight, the moisture content of the wood material increases, and it is difficult to achieve the effect of the present invention, that is, the effect of exhibiting high bending strength even if the pressing time during hot pressing is shortened. is there. If it is less than 2% by weight, the amount of formalin-based adhesive is insufficient, and it is difficult to obtain a wood board with sufficient adhesive strength.

  The compound used together with the formalin adhesive is a compound having a boiling point of 120 to 400 ° C, preferably 140 to 360 ° C, more preferably 160 to 320 ° C.

  As a compound having a boiling point of 120 to 400 ° C., an aqueous compound, preferably a water-soluble polyol is usually used. Examples of water-soluble polyols include propylene glycol, dipropylene glycol, tripropylene glycol, neopentyl glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1 , 4-butanediol, 1,5-pentanediol, hexylene glycol, 1,6-hexanediol, 2-butene-1,4-diol, and other dihydric polyols; glycerin, trimethylolethane, trimethylolpropane, etc. A trivalent polyol etc. are mentioned. These water-soluble polyols may be used as a mixture of two or more.

  When the boiling point of the compound used with the formalin adhesive is less than 120 ° C., the compound is volatilized in the process of producing the wooden board, and it is difficult to achieve the above-described effect of the present invention. Moreover, when the boiling point of the compound to be used exceeds 400 ° C., the solubility of the compound in water is poor, the addition amount is reduced, and it is difficult to achieve the above-described effect of the present invention.

  The amount of the compound having a boiling point of 120 to 400 ° C. in the wood board of the present invention is usually 0.10 to 13% by weight, preferably 0.15 to 9.0% by weight, more preferably 0.30 to 4.0% by weight. %. If it exceeds 13% by weight, it is difficult to achieve the effects of the present invention described above. When the content is less than 0.10% by weight, it is difficult to achieve the above-described effect of the present invention.

  Furthermore, the blending ratio (weight ratio) of the formalin adhesive and the compound having a boiling point of 120 to 400 ° C. is usually 1: 0.005 to 9.0, preferably 1: 0.01 to 4.0, more preferably. 1: 0.02 to 1.2. When the blending ratio is out of the above range, it is difficult to achieve the above-described effect of the present invention.

  Next, the manufacturing method of the wooden board of this invention is demonstrated. In the production method of the present invention, a formalin adhesive and a compound having a boiling point of 120 ° C. to 400 ° C. are added to a wood material, and the resulting mixture is heated and compressed to be molded.

The compound having a boiling point of 120 to 400 ° C. used in the present invention may be (1) added in advance to a wood material, or (2) previously mixed in a formalin adhesive, or (3) a boiling point of 120 to 400 ° C. You may add a compound and a formalin adhesive simultaneously. Among them, (1) a method of adding to a wood material in advance is preferable. In particular, from the viewpoint of maintaining the performance of the wood board and improving the productivity, a compound having a boiling point of 120 to 400 ° C. is made into the wood material before drying the wood material. It is preferable to add.

  The method for adding the compound having a boiling point of 120 to 400 ° C. is not particularly limited, and examples thereof include spraying and dipping. In addition, conditions, such as temperature in that case, are not specifically limited.

  A compound having a boiling point of 120 to 400 ° C. is generally dispersed or dissolved in water and used as an aqueous dispersion or an aqueous solution. The concentration of the compound having a boiling point of 120 to 400 ° C. in the aqueous dispersion or aqueous solution is usually 5 to 60% by weight, preferably 7 to 40% by weight, more preferably 10 to 30% by weight. When it exceeds 60% by weight, it is difficult to uniformly add a compound having a boiling point of 120 to 400 ° C. to the wood material. If it is less than 5% by weight, the moisture content of the wood material increases, and a wood board having sufficient adhesive strength cannot be obtained.

  The amount of the compound aqueous solution having a boiling point of 120 to 400 ° C. to the wood material is usually 3 to 30% by weight, preferably 5 to 15% by weight. When it exceeds 30% by weight, the amount of water increases, and a wood board having sufficient adhesive strength cannot be obtained. When the amount is less than 3% by weight, the amount of the compound to be added is small, and it is difficult to achieve the effect of the present invention described above.

  When a compound having a boiling point of 120 to 400 ° C. is added to the wood material, a known formaldehyde scavenger, rust preventive agent and the like may be added as necessary. Examples of formaldehyde scavengers include ammonium nitrate, urea, melamine, sodium sulfite, and adipic acid dihydrazide. Examples of rust inhibitors include ethylene urea, lauryl phosphoric acid, and benzotriazole.

  Next, the wood material to which the compound having a boiling point of 120 to 400 ° C. is added and the formalin adhesive are mixed.

  The addition amount of the formalin-based adhesive is usually 2 to 25% by weight, preferably 3 to 20% by weight, and more preferably 4 to 18% by weight with respect to the wood material. When it exceeds 25% by weight, the moisture of the woody material increases, and it is difficult to achieve the effect of the present invention. If it is less than 2% by weight, the amount of formalin-based adhesive is insufficient, and it is difficult to obtain a wood board with sufficient adhesive strength. At the time of mixing, known additives useful for improving quality, such as a curing agent and a water repellent, may be added simultaneously.

  The water content of the woody material when mixed with the formalin adhesive is usually 7% by weight or less, preferably 4% by weight or less. If it exceeds 7% by weight, it tends to be difficult to obtain a wood board having sufficient adhesive strength.

  After mixing the formalin-based adhesive, it is usually formed into a board and pre-pressed, and then heated and pressed for a certain period of time by hot pressing, that is, hot-press molding, to produce a wooden board. At this time, the hot press temperature is usually 120 ° C. to 220 ° C., and the pressure is usually 1 to 4 MPa. The pressing time varies depending on the thickness of the product board, and is usually 5 seconds to 30 seconds per 1 mm of the product board. The wood board of the present invention may be a single layer board or a multilayer board.

  The reason why the productivity of the wood board in the present invention is improved is that, by adding a compound having a boiling point of 120 to 400 ° C. to the wood material, the moisture retention of the wood material is improved, and the forming mat when heated and compressed has a predetermined thickness. It is presumed that the time required to reach the temperature can be shortened, the heat conduction to the center of the wood board is accelerated, and the adhesive can be cured in a time shorter than the normal pressing time. The reason why the bending strength of the wooden board is improved is that by adding a compound having a boiling point of 120 to 400 ° C. to the wooden material, the time until the forming mat reaches a predetermined thickness when heated and compressed is shortened. It is presumed that the consolidation of the surface layer can be promoted. In addition, the reason why the compound having a boiling point of 120 to 400 ° C together with the formalin adhesive exhibits the above effect is that the compound having a boiling point of 120 to 400 ° C does not volatilize even at a heating and compression temperature of 120 ° C to 220 ° C. It is presumed that the moisture retaining property of the wood material is maintained until the forming mat reaches a predetermined thickness, so that the time until the forming mat reaches the predetermined thickness can be shortened.

  The wood board of the present invention is a particle board, MDF, hard board or the like manufactured using a formalin-based adhesive, and is used for construction, furniture / furniture, and electrical equipment.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is exceeded. The bending strength was measured according to JIS A 5908.

Example 1:
Apply 10% by weight of 20% by weight propylene glycol (PG) aqueous solution as a compound aqueous solution having a boiling point of 120 to 400 ° C. to the wood chip for the surface layer and the core layer, and a moisture content of 3% by a dryer. % Adjusted. Next, a three-layer particle board was manufactured under the conditions described in Table 1.

Example 2:
In Example 1, 20% by weight of a 1,3-butanediol (BD) aqueous solution as a compound aqueous solution having a boiling point of 120 to 400 ° C. was applied to the wood chips for the surface layer and the core layer by 10% by weight with respect to the wood chips. A particle board was manufactured in the same manner as in Example 1 except that.

Example 3:
In Example 1, except that 20% by weight glycerin (Gly) aqueous solution was applied to the wood chips for the surface layer and the core layer as a compound aqueous solution having a boiling point of 120 to 400 ° C. A particleboard was manufactured as in Example 1.

Comparative Example 1:
In Example 1, the particle board was formed in the same manner as in Example 1 except that the aqueous solution of the compound having a boiling point of 120 to 400 ° C. was not applied to the wood chips for the surface layer and the core layer, and the hot pressing time was 180 seconds. Manufactured.

  The bending strength of the obtained particle board was measured by the above-described bending strength measuring method. The results are shown in Table 2.

  As is clear from the examples and comparative examples in Table 2, the wood material contains a compound having a boiling point of 120 ° C. to 400 ° C. together with a formalin adhesive, so that the press time at the time of hot pressing is shortened. A wooden board showing the bending strength can be obtained. And productivity of a wooden board can be improved.

Claims (7)

In wood boards obtained by heat compression of wood materials (excluding wood chips produced by a wood wool machine) (but excluding wood boards using upholstery paper at the time of heat compression), boiling point of 120 ° C ~ A wood board characterized by containing a compound at 400 ° C. (excluding polyethylene glycol).   The wood board according to claim 1, wherein the compound having a boiling point of 120C to 400C is an aqueous compound.   The wooden board according to claim 2, wherein the aqueous compound is a polyol. A woody material comprising a formalin adhesive and a compound having a boiling point of 120 ° C to 400 ° C (excluding polyethylene glycol) added to a woody material, and the resulting mixture is heated and compressed without using a cover paper. Board manufacturing method.   The manufacturing method of Claim 4 which adds a formalin adhesive after adding a compound with a boiling point of 120 to 400 degreeC to a wooden material.   The production method according to claim 4 or 5, wherein the compound having a boiling point of 120 ° C to 400 ° C is an aqueous compound.   The production method according to claim 6, wherein the aqueous compound is a polyol.