JP2004209660A - Method for manufacturing woody molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a woody molded product enhanced in surface smoothness and bending strength. <P>SOLUTION: The collapsed parts of particles obtained by grinding or cutting a woody base material mechanically or the recessed surface shapes of the particles are expanded before thermally pressed. Concretely, the particles are swollen by water or steam to be expanded and the mutual contact areas of the adjacent particles are increased at thermal pressing to contract the gaps between the particles. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a wooden molded product formed by hot pressing.
[0002]
[Prior art]
A wooden molded body composed of particles made of a wooden material is formed by applying a binder to the particles, depositing the particles to which the binder has been applied to form a mat, and then performing hot pressing. In the particles constituting the wooden molded body formed in this way, many gaps between adjacent particles do not come into contact with each other, and it has been difficult to firmly bond a large number of particles together. As a technique for solving such a problem, in Japanese Patent Application Laid-Open No. H10-157, the voids between the particles are reduced at the time of compression by using particles having a bulk specific gravity of 0.2 or less, and the particles are surface-bonded to other adjacent particles. The figure also shows that the particles themselves are also increased in density near the contact surface.
[0003]
[Patent Document 1]
JP-A-2001-293706
[0004]
[Problems to be solved by the invention]
However, when particles having a bulk specific gravity of 0.2 or less are formed from a woody material, the particles are crushed or cut. However, the particles are crushed by this crushing or cutting process. As a result, when a wood mat is formed from the particle mat made of the particles by hot pressing, the crushed particles are not easily deformed, so that the gap between the wood-molded product particles is not effectively reduced.
[0005]
Therefore, an object of the present invention is to provide a method for producing a woody molded body in which effective void reduction can be obtained by adding a simple step.
[0006]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above-mentioned problem, is a method for producing a wooden molded body, which comprises applying a binder to particles of a wooden material, forming the mixture into a particle mat, and hot-pressing and molding the mixture.
It is characterized by expanding particles before hot pressing.
[0007]
According to such a method, the crushed portion of the particles formed by crushing or cutting the woody material before the hot pressing is expanded, and as a result, the particles themselves are easily deformed, and the entire particle surface is also deformed. And the contact area between adjacent particles during hot press molding is increased. Therefore, the voids between the particles are effectively reduced, and a wooden molded article having excellent surface smoothness and improved bending strength can be obtained.
[0008]
Further, the invention of claim 2 for solving the above-mentioned problem is a method for producing a wooden molded article,
A swelling step of swelling the particles of the woody material with an aqueous solution or steam to form swollen particles,
After the swelling step, the swelling particles are dried, a binder is applied to the particles to form a binder, and a binder application step is performed.
After the binder application step, the method further comprises: a hot pressing step of forming the shaped particles into a particle mat having a predetermined shape, and then hot pressing the particle mat to form a wooden molded body.
[0009]
According to such a method, by swelling the particles with a liquid or vapor, the crushed portion of the particles formed by mechanically crushing or cutting the woody material is expanded, and as a result, the particles themselves are swelled. The particles are easily deformed, the hardness of the entire particle surface is made uniform, and the contact area between adjacent particles during hot press molding is increased. Therefore, the voids between the particles are effectively reduced, and a wooden molded article having excellent surface smoothness and improved bending strength can be obtained.
[0010]
The invention of claim 3 for solving the above-mentioned problem is the method for producing a woody molded product according to any one of claims 1 and 2, wherein the woody material is kenaf core.
[0011]
According to such a method, particles formed by crushing or cutting a kenaf core having a lower specific gravity than wood have a large crushed portion. For this reason, by expanding the particles, voids between the particles can be effectively reduced, and a wooden molded article having excellent surface smoothness and improved bending strength can be obtained.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIG. The woody compact 6 is obtained by hot pressing a particle mat 5 composed of the particles 1 coated with the binder 2, and is manufactured by the process shown in FIG. The particles 1 are prepared by mechanically pulverizing or cutting wood, which is a woody material, and stems. The size of the particles 1 is 1 to 3 mesh (1 mesh is a size that passes through a sieve of 1 mm × 1 mm), and the specific gravity is preferably 0.1 to 0.3.
[0013]
In the present invention, the crushed portion of the particle 1 formed by mechanically pulverizing or cutting a wooden material is expanded.
[0014]
There are various methods for swelling, and a method of swelling the particles 1 with water or steam is effective. For swelling, water is put into the steam pot 3 so that the weight becomes 70% or more based on the weight of the particles 1, and steam treatment is performed at 100 to 120 ° C for 10 to 20 minutes. In addition, the swelling may be achieved by heating the particles 1 immersed in water by vibrations caused by electromagnetic waves. The swelling of the particles 1 before and after swelling is preferably 110 to 140%, and the water content of the particles 1 is preferably 100 to 200%.
[0015]
Next, the swollen particles 1 are dried so as to have a water content of 50% or less so as to be formed into particles, and a binder 2 is applied. The weight ratio of the particles 1 to the binder 2 is preferably 7: 3, and preferably 8: 2 to improve smoothness.
[0016]
As the binder resin 3, a thermoplastic resin such as polylactic acid or acrylic resin, or a thermosetting resin such as melamine resin, urea resin, or phenol resin is used.
[0017]
As the binder application method, a known method is used, for example, a method of spraying the binder in a liquid state such as a dispersion or an emulsion, or a method of mixing the particles 1 and the liquid binder in a rotating body and stirring.
[0018]
The particles 1 that have undergone such a process are deposited by a known method to form a particle mat 5, and then hot-pressed with a known upper and lower mold to form a wooden molded body 6. The mold temperature in the hot press is equal to or higher than the melting or curing temperature of the binder 2, and for example, 160 to 180 ° C is preferable for polylactic acid having a melting temperature of 150 ° C. The pressing force is 10 kg / cm ² or more, and the pressurizing time depends on the thickness of the wooden molded product to be molded.
[0019]
According to this manufacturing method, the contact area between the adjacent particles 1 increases during hot pressing of the expanded particles 1, and the bonding strength between the particles 1 increases. Therefore, the voids between the particles 1 of the wooden molded body 6 are reduced, and the wooden molded article 6 having improved surface smoothness and improved bending strength is obtained.
[0020]
【Example】
The kenaf core, which is the core material of the kenaf wood material, is pulverized to a size of 1 to 3 mesh with a hammer mill to obtain particles having a bulk specific gravity of 0.17. 50 g of the particles and 100 g of water are put into a steam pot and subjected to a steam treatment at 120 ° C. for 20 minutes to expand the particles. Next, the swollen particles are dried in an oven at 60 to 80 ° C. for 3 hours so that the water content becomes 50% or less, and then the particles and the binder are sprayed on the particles so that the weight ratio becomes 7: 3. Apply. The particles coated with the binder are formed into a particle mat having a thickness of 3 mm, and the particle mat is subjected to hot pressing with a vertical die under the conditions of a mold temperature of 160 to 180 ° C., a pressure of 10 kg / cm ² and a pressing time of 60 seconds. Then, a wooden molded product having a thickness of 2 mm was formed.
[0021]
As a comparative example, a wooden molded body was manufactured under the same conditions except that the particles were not expanded before hot pressing.
[0022]
The bending strength, flexural modulus, surface roughness, and non-contact area ratio of the obtained wooden molded body of the present invention and the wooden molded body of the comparative example were measured. FIG. 2 shows the measurement results. The surface smoothness was measured with a surface roughness meter (according to JIS-B0601). The smaller the surface roughness, the better the surface smoothness. The non-contact area ratio was obtained by reading the surface of the molded article with a scanner, calculating the surface area of the wooden molded article and the non-contact area, and defining the ratio of the non-contact area to the surface area of the molded article. The smaller the non-contact area ratio, the smaller the gap between particles. Comparing the wood molded product of the present invention and the wood molded product of the comparative example with the same density of 0.56 g / cm ³ , the wood molded product of the present invention has bending strength, Both the flexural modulus and the surface roughness are superior to those of the comparative example in which the particles are not expanded before hot pressing. This indicates that the voids between adjacent particles of the wood molded article molded according to the present invention were effectively reduced as compared with the comparative example, and as a result, the surface smoothness and the wooden molded article having improved strength were obtained. It has become.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing steps of a method for producing a woody molded product of the present invention.
FIG. 2 shows measurement results of the present invention and a comparative example.
[Explanation of symbols]
1 ... Particle 2 ... Binder

Claims (3)

A method for producing a wooden molded body, in which a binder is applied to particles of a wooden material, and the mixture is formed into a particle mat, and then hot pressed and molded.
A method for producing a wooden molded body, comprising expanding particles before hot pressing. A method for producing a wooden molded article, comprising:
A swelling step of swelling the particles of the woody material with an aqueous solution or steam to form swollen particles,
After the swelling step, the swelling particles are dried, a binder is applied to the particles to form a binder, and a binder application step is performed.
After the binder application step, after the forming particles are formed into a particle mat of a predetermined shape, a hot pressing step of hot pressing the particle mat to form a wood molded body. . 3. The method according to claim 1, wherein the wood material is kenaf core.

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