JP3322518B2 - Artificial wood and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inexpensive high-strength artificial wood which can be used as a substitute for high-strength wood, such as pine and yakar, which are indispensable in industry but tend to be browned worldwide, and their production. About the method.

[0002]

2. Description of the Related Art As artificial wood, a particle board made mainly of cut wood chips and a fiber board made mainly of unwoven pulp are commercially available. However, these materials are weak in strength, and in particular, have extremely low water absorption strength, so that they cannot be used as substitutes for high-strength wood for outdoor use, such as planks used in shipyards and pallets laid on the bottom of heavy loads.

[0003]

[Problems to be solved by the invention]

1) Improvement of strength, especially water absorption strength Conventional artificial wood is often used for interior wall materials of houses and furniture furniture, so high strength is not so required, and water absorption strength is also a problem for indoor use. Was not turned on.
As a result of actually purchasing a commercially available fiberboard with excellent strength and conducting a strength test, the dry bending strength is 300 ~
Although the water absorption was 500 kg / cm ² , the water absorption strength could not be measured because the water was broken by hand after water absorption. 2) Cost reduction and mass production The pine and yakar used for the above-mentioned sideboards are quite expensive, and the import destinations in North America and the like have a strong tendency to prohibit logging from the viewpoint of nature protection, and it is becoming difficult to obtain them. is there.

[0004] 3) Reduction of Directional Deviation of Strength [0004] Natural wood greatly differs in strength in the direction of annual rings, that is, the grain direction and the grain direction. As a result, waste materials are increasing, and on-site workers are also very careful. An object of the present invention is to solve the above-mentioned problems and to provide an artificial wood having excellent strength, particularly excellent water absorption strength, and a manufacturing method capable of manufacturing the same at a reduced cost.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing artificial wood by compression-molding wood powder to which a binder has been added, wherein the wood powder raw material has an average particle size distribution of 100 to 500 μm.
m coarse-grained wood flour and fine-grained wood with an average particle size distribution of 10 to 50 μm
Flour and 1/3 to 1 of the average particle size of the coarse wood flour
Crushing and classifying into fine wood powder having an average particle size of / 10, and adding 10 to 60 parts by weight of fine wood powder to 100 parts by weight of coarse wood powder to promote close packing between wood powders. A method for producing a high-strength artificial wood characterized by the fact that synthetic wood obtained by compression-molding wood flour to which a binder has been added is characterized in that the wood flour is
The average particle size distribution is 10 to 50 with respect to coarse wood powder having an average particle size distribution of 100 to 500 μm and 100 parts by weight of the coarse wood powder.
10 μm fine wood flour having a mean particle size of 1/3 to 1/10 of the mean grain size of the coarse wood flour.
It can be achieved by a high-strength artificial wood which promotes mutual close packing of wood powder in addition to 〜60 parts by weight.

The wood used as a raw material for the wood flour used herein is not particularly limited, and may be natural wood, waste wood generated from demolition houses or sawmills, wind-down trees, dead wood, etc., cedar, lauan. And the like, and as the thermosetting resin added as needed, epoxy-based, polyester-based waste FRP and the like can be mentioned. Further, among the wood flours, the average grain size distribution of the coarse wood flour and the fine wood flour is 100 to 500 μm,
It is preferable to use one having a particle size of from 50 μm to 50 μm. In particular, it is necessary that the average particle size of the fine wood powder is 1/3 to 1/10 of that of the coarse wood powder. The average particle size of the thermosetting resin is preferably in the range of 3 to 30 μm, and the compounding amount is preferably 30 to 70 parts by weight based on 100 parts by weight of the total amount of wood powder.

Further, in the present invention, it can be produced by one-pass wet continuous pulverization of pulverized coarse wood powder, pulverized fine wood powder, and pulverized thermosetting resin fine particles with one pulverizer. Such a pulverizing process is performed using, for example, an apparatus as shown in FIG. 4 (Mitsubishi Ultra Fine Mill-hereinafter referred to as UF mill-). The UF mill has an inner cylinder and an outer cylinder equipped with stirring blades, and fills the gap with crushed balls,
Rotate the inner cylinder and outer cylinder individually or simultaneously,
This is a horizontal ultrafine mill that continuously pulverizes and continuously discharges the supplied powder or powder slurry.

FIG. 4 shows an operation system in which the inner cylinder of the UF mill is independently rotated to perform wet continuous pulverization. The crushed material is continuously supplied from a raw material hopper 1 to a UF mill by a feeder 2, and the slurry medium (water in the present invention) is continuously supplied from a tank 3 to a UF mill by a supply pump 4. The fine slurry crushed by the crushing balls 7 filled in the gap between the UF mill outer cylinder 5 and the rotating UF mill inner cylinder 6 is separated from the crushing balls by a discharge slit 8 provided concentrically around the end of the mill. Only the pulverized powder is continuously discharged and collected in the product tank 9. According to this method, coarsely pulverized wood powder, finely pulverized wood powder, and finely pulverized thermosetting resin are each continuously pulverized by a separate pulverizer and uniformly mixed and dispersed in a later step, which is necessary for manufacturing equipment and the like. Cost can be reduced.

Further, in a preferred embodiment of the present invention, in the operation of the UF mill, the supply port 10 for the raw wood flour and the FRP is arranged in the flow of the crushing material in FIG. 5 from the upstream side to the downstream side. By changing the residence time in the mill and adjusting the pulverized particle size, the pulverized slurry of two types of raw materials (wood flour, FRP) and three particle sizes (two types of wood flour, one FRP) can be milled. Continuous production can be performed by one unit. Further, the uniform mixing and dispersion of the three-particle-size pulverized powder can be continuously processed by one mill by the random stirring effect of the inner and outer cylinder stirring blades and the grinding balls of the UF mill.

[0010]

The present invention will be described in more detail below. (1) Improvement of strength, especially water absorption strength By mixing coarse wood flour and fine wood flour, fine wood flour enters gaps of coarse wood flour, so-called “close-packed structure” between wood flours. By forming, the denseness is greatly improved, thereby improving the overall strength. Further, by adding a thermosetting resin finer than the fine-grained wood powder, the resin powder enters the voids of the fine-grained wood powder to further promote the close-packed structure, and at the same time, the resin powder is hardened by the heat at the time of compression molding. Strength and rigidity can be improved. An isocyanate-based binder having strong water repellency is used as a binder for bonding wood powders. Due to the water repellency of the binder and the denseness due to the close-packed structure, the water absorption of the final product can be greatly reduced, and the water absorption strength is improved.

(2) Cost reduction and mass production Recently, typhoon-induced fallen trees and dead trees around large cities due to waste gas (such as SO ₃ ) have increased, and effective use has been urgently required in terms of preventing secondary disasters. ing. Also, treatment of waste FRP ships, which are FRP products that are representative of thermosetting resins, and waste tubs has become a major social problem. The present invention can use waste wood and waste FRP, which are generated in a large amount and are waiting for effective treatment, as main raw materials. Therefore, the artificial wood is inexpensive, and mass production is possible. It has great social significance from the viewpoint of resource recycling. (3) Reduction of Directional Deviation of Strength The present invention is based on a uniform close-packed structure made of coarse wood powder, fine wood powder and FRP powder, so that it is not largely influenced by the direction of the annual rings, Sex deviation can be greatly reduced.

<Optimal particle size ratio and optimum compounding ratio for forming a close-packed structure> The optimum particle size ratio for a close-packed structure can be theoretically examined in the case of a true sphere. In the case of powder, it was difficult to conduct a theoretical study and an experimental study was conducted. Curve in Figure 2 [I] average particle diameter (D ₅₀₎ of fine wood average particle size of the _S and coarse wood (D
Shows the relationship between the ₅₀₎ the ratio α _{[= (D 50) S / (} D 50) B ] and _B and prototype compressive strength ratio of the artificial timber. still,
The mixing ratio β of fine wood (fine wood / coarse wood), the amount of binder added, and molding conditions were all constant. Curve [II] shows the ratio between the average particle size (D ₅₀ ) _F and (D ₅₀ ) _S of the FRP powder. As is apparent from FIG. 2, the strength increases remarkably as α decreases, and this is due to the effect of forming a close-packed structure in which fine-grained wood enters pores of coarse-grained wood.
When the FRP powder was mixed, the strength was improved by about 40% due to the thermosetting effect. Further, the appropriate value of α is 1/3 or less from the viewpoint of strength, and 1/10 or more from prevention of increase in grinding power.
That is, α = 1/3 to 1/10 was determined to be appropriate.

FIG. 3 shows a test of the effect of the mixture ratio β with α = 1/6 constant. In the curve [III] in which the FRP powder was not mixed, β = 0.1 to 0.6 was determined to be appropriate.
Although the porosity at the time of filling a true sphere is 20 to 40%, it is presumed that the wood powder is fibrous and the appropriate range has been expanded for compression molding. In the case of the curve [IV] of FRP powder mixing, although the strength increases with an increase in the FRP powder mixing ratio,
Since the pulverizing power of the RP powder is considerably large, the mixing of 60% by weight or more causes an increase in cost, so that β = 0.2 to 0.5 is appropriate.

[0014]

The present invention will be described in more detail with reference to the following examples. (Embodiment 1) FIG. 1 is a flow sheet schematically showing the method of the present invention. As the waste wood, raw wood generated at the time of house dismantling was used as a raw material, and pulverized into coarse wood powder having an average particle size of 150 μm and fine wood powder having a average particle size of 25 μm. As the waste FRP, a 5 μm FRP powder obtained by pulverizing a waste bath tub discharged as oversized garbage from a household was used. The binder used was a water-repellent isocyanate-based binder (manufactured by Oshika Shinko Co., Ltd.). The mixing ratio is 100 for coarse wood powder and 3 for fine wood powder.
0, FRP powder 30, and binder 5 (all by weight). After uniformly mixing and stirring these four materials, a heat compression molding machine (pressure 15 kg / cm ² , temperature 150 ° C.)
And made into artificial wood. Table 1 shows the properties of the obtained artificial wood. Table 1 also shows characteristic values of natural pine wood and commercially available artificial wood.

[0015]

[Table 1]

(Embodiment 2) Using the UF mill of FIG. 5, the raw material hoppers 11, 12, and 13 are filled with a raw material for FRP, a raw material for wood powder (for fine powder), and a raw material for wood powder (for coarse powder), respectively. did. As shown in FIG. 5, the positions of the supply ports for the various raw material powders are L _P ,
_LWS and _LWB were installed. Since it is necessary to increase the residence time in the mill for finer pulverization, the position of the supply port is set to be L _P > L _WS > L _WB and away from the discharge port. FIG. 6 is a schematic diagram of each pulverizing characteristic when wood powder and FRP powder are pulverized in a UF mill batch (batch type) pulverization test under the same operating conditions (mill rotation speed, ball amount (rate), etc.). At the time of batch pulverization, finer powder is obtained as the pulverization time is longer as shown in the figure. Required for artificial wood production,
The coarse wood powder particle size is D _WB , the required grinding time is t _WB , the fine wood powder particle size is D _WS , the required grinding time is t _WS , and the FRP powder particle size is D _P ,
When the required grinding time is t _P , the required grinding time is t _WB :
t _WS : t _P = 1: 4: 8. These results are shown in FIG.
If the required grinding particle size is adjusted by adjusting the required grinding time and the residence time in the mill, the ratio of the distance between the supply port and the discharge port is required to be reflected in the continuous grinding conditions such as What is necessary is just to make it the ratio of batch grinding time. Therefore, in order to obtain the particle size and mixing ratio of the raw material powder shown in Table 2 below, UF
L _WB : L _WS : L _P
By arranging them at the position of = 1: 4: 8, drying of the target artificial wood and slurry before molding were continuously produced by single-stage pulverization.

[0017]

[Table 2]

[0018]

Thus, the artificial wood obtained by the method of the present invention has the following excellent properties: (1) Compared with the conventional commercial artificial wood, the strength, particularly the water absorption strength, is remarkably excellent. ) It has almost the same strength as natural pine wood, the directionality of the strength is small, and the weakest strength is better than natural pine wood. (3) Waste wood such as wind-down trees and dead trees are difficult to treat and society Waste FRP products in question (waste FRP ships, waste tubs)
Since it is used as a main raw material, it can be manufactured at low cost and has great social significance in terms of recycling of waste. (4) Especially when using a UF mill, the manufacturing cost can be significantly reduced (almost half of the conventional method).

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing an example of a manufacturing process according to the method of the present invention,

FIG. 2 is a graph showing the relationship between the average particle size ratio of raw materials and the strength ratio for artificial wood obtained by the method of the present invention.

FIG. 3 is a graph showing the relationship between the mixing ratio of raw materials and the strength ratio for artificial wood obtained by the method of the present invention;

FIG. 4 is a conceptual diagram showing a one-pass wet continuous pulverizer using a UF mill,

FIG. 5 is a schematic diagram illustrating a means for adjusting the particle size by changing the arrangement of the raw material supply ports;

FIG. 6 is a graph showing the respective pulverization characteristics when wood powder and FRP powder are pulverized by a UF mill batch pulverization test.

[Explanation of symbols]

 1: Material hopper 2: Feeder 3: Tank 4: Supply pump 5: UF mill outer cylinder 6: UF mill inner cylinder 7: Grinding ball 8: Discharge slit 9: Product tank

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideo Tsunoda 5-717-1 Fukahori-cho, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (56) References JP-A-53-13681 (JP, A) Kaihei 7-9467 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B27N 1/00-5/00 B27L 11/00

Claims (9)

(57) [Claims] 1. A method for producing artificial wood by compression-molding wood powder to which a binder has been added, wherein the wood powder raw material has an average particle size.
Coarse wood flour with distribution of 100-500μm and average particle size distribution
Fine-grained wood flour having a particle size of 10 to 50 μm and having an average particle size of 1/3 to 1/10 of the average grain size of the coarse-grained wood flour is crushed and classified. 1 for part
A method for producing high-strength artificial wood, characterized in that 0 to 60 parts by weight of fine wood powder is added to promote close packing between wood powders. 2. The method for producing a high-strength artificial wood according to claim 1, wherein the rigidity is increased by adding a thermosetting resin powder having an average particle size of 1/3 to 1/10 of the average particle size of the fine wood powder. . 3. The method according to claim 1, wherein waste wood such as wind-down wood, standing wood or house dismantled wood is used as wood flour raw material, and waste FRP generated in large quantities from waste boats and waste bath tubs is used as thermosetting resin raw material. 3. The method for producing a high-strength artificial wood according to 2. 4. A wood flour raw material is pulverized and classified by wet pulverization into coarse wood flour and fine wood flour having an average particle size of 1/10 to 1/3 of the average grain size of the coarse wood flour. , Coarse wood flour 100
10 to 60 parts by weight of fine wood flour is added to the parts by weight to promote the close packing of the wood flour, and heat having an average particle size of 1/10 to 1/3 of the average particle size of fine wood flour In a method for producing artificial wood, which comprises adding curable resin powder to increase rigidity, one-pass continuous wet production of pulverized coarse wood powder, fine wood powder, and pulverized thermosetting resin fine particles with one pulverizer. A method for producing high-strength artificial wood, characterized by the following. 5. A pulverizing raw material supply point to a pulverizer is installed at an arbitrary point from an upstream side to a downstream side to adjust a residence time inside the pulverizer, thereby reducing FRP powder, fine powder wood, and coarse powder wood. The method for producing a high-strength artificial wood according to claim 4, wherein the uniformly mixed and dispersed slurry is subjected to one-pass continuous wet production with one pulverizer. 6. The method according to claim 4 or 5, wherein waste wood such as wind-down trees, dead wood or house demolition wood is used as a raw material for wood flour, and waste FRP generated in large quantities from waste ships and waste tubs is used as a raw material for thermosetting resin. The method for producing a high-strength artificial wood according to the above. 7. An artificial wood obtained by compression-molding wood powder to which a binder has been added, wherein the wood powder has an average particle size distribution of 100.
With respect to coarse wood flour of ~ 500 µm and 100 parts by weight of the coarse wood flour , fine wood flour having an average particle size distribution of 10 ~ 50 µm
And 10 to 60 parts by weight of fine wood flour having an average grain size of 1/3 to 1/10 of the average grain size of the coarse wood flour is added to promote mutual close packing of wood flour. Strength artificial wood. 8. The high-strength artificial wood according to claim 7, further comprising a thermosetting resin powder having an average particle size of 1/3 to 1/10 of the average particle size of the fine wood powder. 9. A method in which waste wood such as wind-down wood, dead wood or house demolition wood is used as wood flour raw material, and waste FRP generated in large quantities from a waste ship or waste tub is used as a thermosetting resin raw material for a binder. Item 7. High-strength artificial wood according to item 7 or 8.