JP5503582B2 - Manufacturing method of colored wood - Google Patents

Description

  The present invention relates to a method for producing colored wood.

  Conventionally, as proposed in Patent Document 1, there is known a method of coloring wood by heat-treating it in a high-temperature and high-pressure steam atmosphere. In the final stage of the heat-treatment, when the pressure is reduced from a high-pressure state to atmospheric pressure. In addition, there is a problem that the surface of the wood is excessively dried to cause dry cracking. In view of this, the present applicant has proposed a method in which the wood is colored in a high-temperature and high-pressure steam atmosphere, and then the colored wood is submerged in a high-temperature and high-pressure state before the pressure is lowered (see Patent Document 2).

JP-A-8-155909 JP 2010-6045 A

  According to the method of Patent Document 2, since the colored wood is submerged before pressure reduction, drying of the wood surface during pressure reduction is suppressed, and dry cracking of the color wood is reduced. Further, since the colored wood is rapidly cooled by submerging the colored wood, there is an effect that the processing time can be shortened. However, as a result of subsequent studies, when this method is applied to wood with high water retention, the dry cracking can be reduced, but because of its high water retention, the moisture content of the wood increases. A problem due to high water content was found in the next machining process. Specifically, it is pointed out that the laminated adhesion of the treated wood is not sufficient, the veneer adheres at the time of slicing, or cracks due to cracks occur in the veneer.

  This invention is made | formed in view of the situation as mentioned above, and makes it a subject to provide the manufacturing method of the colored wood which can reduce the dry crack of wood and can be adjusted to a suitable moisture state.

In order to solve the above-mentioned problems, the colored wood manufacturing method of the present invention is characterized by manufacturing colored wood through the following steps in sequence.
Process A: The process of heating and pressurizing the sealed space containing the wood to color the wood by high-pressure steam treatment under an atmospheric pressure higher than atmospheric pressure,
Step B: Step of reducing the atmospheric pressure in the sealed space,
Step C: a step of introducing water into the enclosed space before the temperature of the wood raised by the high-pressure steam treatment in Step A reaches room temperature, and submerging the wood under an atmospheric pressure atmosphere,
Step D: A step of draining the water in the sealed space and reducing the atmospheric pressure in the sealed space to a pressure lower than the atmospheric pressure.
In this method for producing colored wood, in step B, it is preferable to reduce the atmospheric pressure in the sealed space to a pressure lower than atmospheric pressure.
Moreover, it is preferable to repeat the process C and the subsequent process D as one cycle for a plurality of cycles.

  ADVANTAGE OF THE INVENTION According to this invention, the dry crack of colored wood can be reduced and colored wood can be adjusted to a suitable moisture state.

It is the flowchart which showed one Embodiment of the manufacturing method of the colored wood of this invention in process order. It is the schematic block diagram which showed an example of the processing apparatus of wood. It is the figure which showed the time-dependent change of the atmospheric pressure in a pressure vessel at the time of manufacturing colored wood according to the flowchart of FIG. 1, and the temperature of wood. It is the schematic diagram which showed an example of the loading state of the wood accommodated in the pressure vessel of the processing apparatus of wood. It is the flowchart which showed another one Embodiment of the manufacturing method of the colored wood of this invention in process order. It is the figure which showed the time-dependent change of the atmospheric pressure in a pressure vessel at the time of manufacturing colored wood according to the flowchart of FIG. 5, and the temperature of wood.

  As described above, the colored wood manufacturing method of the present invention manufactures colored wood through Step A to Step D in sequence. Hereinafter, the manufacturing method of the colored wood of this invention is demonstrated along drawing. FIG. 1 is a flowchart showing an embodiment of a method for producing colored wood according to the present invention in the order of steps, and FIG. 2 is a schematic configuration diagram showing an example of a wood processing apparatus. FIG. 3 is a diagram showing changes over time in the atmospheric pressure in the pressure vessel and the temperature of the wood when the colored wood is manufactured according to the flowchart of FIG. 1. In the figure, the broken line is the atmospheric pressure in the pressure vessel, and the solid line is the temperature of the wood.

The wood processing apparatus 1 of FIG. 2 includes a pressure vessel 2 that forms a sealed space, and a cart 3 to which wood 20 is bound and fixed is disposed. The pressure vessel 2 is a cylindrical body made of, for example, stainless steel so as to be able to withstand a high temperature and high pressure state, and an openable / closable lid for inserting and removing the carriage 3 is attached. The pressure vessel 2 includes a water vapor supply valve 5 that communicates with a water vapor generation source 4, a pressure reducing valve 7 that communicates with a vacuum pump 6, a water supply valve 9 that communicates with a water tank 8, a water vapor exhaust valve 10 that communicates with an atmospheric pressure atmosphere, water And a drain valve 11 for draining water. Further, a heat source such as a heater is incorporated in the pressure vessel 2 so that the atmospheric temperature of the sealed space of the pressure vessel 2 can be raised.
<Wood>

  The wood to which the method for producing colored wood of the present invention is applied is wood made of various tree species used for building materials such as floors, walls, and ceilings, construction members, furniture, and crafts. As a form of wood, what was processed into plate shape can be illustrated, for example, a flitch can be mentioned.

As shown in FIG. 2, the timber is stacked in a plurality of stages on the carriage 3, and is bound and fixed and stored in the pressure vessel 2. At this time, in order to increase the processing efficiency, the timbers 20 are arranged at predetermined intervals vertically and horizontally so that the adjacent timbers 20 do not contact each other. For example, as shown in FIG. 4, the timbers 20 placed on each stage are arranged at intervals so as not to contact each other, and the stacking is performed with a spacer 21 interposed so that the upper and lower timbers 20 do not contact each other. For example, the timber 20 can be stacked and loaded.
<Temperature increase and pressure increase process (process A)>

  In this step, the sealed space containing the wood is heated and pressurized to color the wood by high-pressure steam treatment under an atmospheric pressure higher than atmospheric pressure. When wood stored in a sealed space comes into contact with high-temperature and high-pressure water vapor, cellulose, hemicellulose, and lignin, which are wood components, are altered and the wood is colored brown.

Specifically, the temperature of the sealed space in the pressure vessel 2 is raised with a heat source. Further, the pressure reducing valve 7, the water supply valve 9, the water vapor exhaust valve 10 and the drain valve 11 are closed, and the water vapor supply valve 5 is opened to introduce water vapor such as saturated water vapor from the water vapor generation source 4 to the pressure vessel 2. It is also possible to open the pressure-reducing valve 7 and perform evacuation to introduce water vapor. The atmospheric temperature in the pressure vessel 2 into which water vapor has been introduced is adjusted to, for example, 120 ° C. or higher so that the wood 20 can be colored. From the viewpoint of suppressing coloring variation and deterioration of the wood 20, it is preferably 120 ° C to 230 ° C, more preferably 130 ° C to 200 ° C, and particularly preferably 140 ° C to 160 ° C. The atmospheric pressure in the pressure vessel 2 is higher than atmospheric pressure, and the upper limit varies depending on the type of wood 20 to be treated, but can be set to 3 MPa, for example, based on atmospheric pressure. After the introduction of steam, the steam supply valve 5 is closed.
The temperature of the wood 20 in the pressure vessel 2 rises as the ambient temperature rises as shown in FIG.
<Holding process>

In the present embodiment, after the temperature of the sealed space is raised and increased, the high temperature and high pressure state is maintained for a certain time. The holding time varies depending on the amount of wood to be treated, the size, the tree species, etc., but can be, for example, 30 minutes or more. Considering the processing efficiency, wood degradation, etc., the time can be 5 hours or less. It is preferably 1 hour or more and 4 hours or less, and particularly preferably 2 hours or more and 3 hours or less. By maintaining the high-temperature and high-pressure state in such a range, the coloring of the wood becomes good and the dimensional stability of the colored wood is improved.
<Temperature lowering and step-down process (Process B)>

In this step, the atmospheric pressure in the sealed space is reduced from a high pressure state to atmospheric pressure.
Specifically, the steam exhaust valve 10 is opened to lower the atmospheric pressure. By opening the steam exhaust valve 10, the ambient temperature is also lowered, and the temperature of the wood 20 is lowered by natural cooling of the wood 20.

Although not shown, after the atmospheric pressure in the sealed space is reduced to atmospheric pressure, it can be further reduced to a pressure lower than atmospheric pressure. By such a decompression process, the inside of the wood can be effectively cooled. In addition, it is effective to impregnate the wood structure with water in the first submerged step. As a result, in addition to being effective in reducing the surface cracks of the wood, the wood can be cooled more quickly. Specifically, the depressurization process closes the steam exhaust valve 10 of the pressure vessel 2, opens the depressurization valve 7, and drives the vacuum pump 6 to depressurize, for example, about -1 MPa to -0.3 MPa on the basis of atmospheric pressure. For example, the sealed space in the pressure vessel 2 is evacuated and the state is maintained for about 1 to 10 minutes.
<First submerged process (process C)>

  In this step, water is introduced into the sealed space before the temperature of the wood raised in the temperature raising and pressure raising steps reaches room temperature, and the wood is submerged in an atmospheric pressure atmosphere. By submerging the wood before the temperature of the wood reaches room temperature, the wood can be cooled in a short time as shown in FIG. Moreover, since the wood structure is impregnated with water, dry cracking of the wood can be reduced. Here, room temperature is generally 15 ° C. to 25 ° C.

  Specifically, the submergence of the wood is performed by opening the water supply valve 9 and introducing water from the water tank 8 into the pressure vessel 2. At that time, when the atmospheric pressure is reduced to less than atmospheric pressure in the temperature lowering and lowering steps, water can be introduced into the pressure vessel 2 by closing the pressure reducing valve 7 and opening the water supply valve 9 in the reduced pressure state. The introduction of water gradually reduces the degree of pressure reduction, and finally the atmospheric pressure in the pressure vessel 2 becomes atmospheric pressure. It is also possible to introduce water into the pressure vessel 2 by opening the water supply valve 9 after opening the steam exhaust valve 10 and the like from the depressurized state to set the atmospheric pressure in the pressure vessel 2 to atmospheric pressure.

  When the atmospheric pressure is not reduced below atmospheric pressure in the temperature lowering and depressurizing steps, water may be introduced by opening the water supply valve 9 while the atmospheric pressure is reduced to atmospheric pressure, or after the pressure is reduced to atmospheric pressure, the water supply valve 9 You may open and introduce water. When water is introduced in the middle of pressure reduction, it can be performed after the atmospheric pressure becomes, for example, 0.05 MPa or less on the basis of atmospheric pressure.

The amount of water introduced into the pressure vessel 2 is such that the wood 20 is completely submerged. The submergence time of the wood 20 is not particularly limited, and after the wood 20 is submerged, the water supply valve 9 may be immediately closed and the drainage valve 11 may be opened to drain the water, or the water supply valve 9 may be closed for about 1 to 10 minutes. It can be submerged. In addition, water can be circulated in the pressure vessel 2 by introducing the water into the pressure vessel 2 and overflowing the introduced water from the pressure vessel 2 to drain the water. In this case, since fresh water is always supplied to the wood 20, the cooling effect of the wood 20 is improved.
<First decompression step (step D)>

  The wood that has undergone the first submersion process has a high water content due to the water impregnation of the wood structure accompanying the submersion of the wood. Therefore, in the first decompression step, the water in the sealed space is drained and the wood submerged in the first submersion step is put into a non-submerged state, and the atmospheric pressure in the sealed space is reduced to a pressure lower than the atmospheric pressure. By this decompression, the inside of the wood can be effectively cooled. Moreover, since the water impregnated in the wood structure evaporates, the wood that has undergone the first depressurization step has a lower moisture content than the wood immediately after the first submersion step. For this reason, when wood having high water retention is used as the treated wood, the moisture content of the wood is high at the stage after the first submersion process, but the moisture content of the wood is reduced by going through the first decompression process. It is possible to adjust to a proper water content state by adjusting it to a lower level. Therefore, in the case of collective bonding using the wood manufactured by this method, it is possible to reduce adhesion failure due to high moisture content. In addition, it is possible to suppress the occurrence of problems such as adhesion of single plates to each other at the time of slicing or cracks caused by cracks.

Specifically, in the first decompression step, the drain valve 11 is opened to drain the water in the pressure vessel 2 so that the wood 20 is not submerged. Next, the drain valve 11 is closed, the pressure reducing valve 7 is opened, and the vacuum pump 6 is driven to evacuate. The negative pressure degree and the pressure reduction time are appropriately set in the range of about -1 MPa to -0.3 MPa and about 1 minute to 10 minutes, respectively, according to the target moisture content. The target moisture content is set to such an extent that dry cracking does not occur in the wood 20.
<Colored wood>

  After completion of the decompression, the steam exhaust valve 10 is opened to bring the inside of the pressure vessel 2 into an atmospheric pressure atmosphere, the lid is opened, and the carriage 3 is carried out to obtain the target wood 20. The obtained wood 20 is colored wood, and is adjusted to an appropriate water-containing state. In addition, the defect rate due to dry cracking is also kept low.

  FIG. 5 is a flowchart showing another embodiment of the method for producing colored wood according to the present invention in the order of steps. FIG. 6 is a diagram showing changes over time in the atmospheric pressure in the pressure vessel and the temperature of the wood when the colored wood is manufactured according to the flowchart of FIG. In the figure, the broken line is the atmospheric pressure in the pressure vessel, and the solid line is the temperature of the wood.

  In the flowchart of FIG. 5, the steps from the temperature raising / pressurizing step to the first pressure reducing step are the same as those in FIG. 1, and the second submerging step and the second pressure reducing step are further added. The second submersion step and the second depressurization step are substantially the same as the first submersion step and the first depressurization step, respectively, and this cycle is repeated with one submersion of the wood and subsequent decompression of the wood in a non-submersion state as one cycle. ing.

  In this embodiment, as shown in FIG. 6, the temperature of the wood at the end of the second decompression step is compared with that at the end of the first decompression step, by repeating the submersion of the wood and the subsequent decompression of the wood in a non-submerged state. Further lower. Since the temperature of the timber at the end of the second decompression step is closer to room temperature, dry cracking that occurs in the timber carried out of the pressure vessel is further reduced. In this embodiment, this cycle is repeated twice, but the wood can also be cooled by repeating three or more times.

While the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, the moisture adjustment effect of wood can be enhanced by intentionally introducing water vapor into the pressure vessel in the step of reducing the atmospheric pressure in step B to atmospheric pressure to raise the surface temperature of the wood. The effect can be further enhanced by intermittently introducing the water vapor.
Examples of the present invention are shown below, but the present invention is not limited thereto.

<Example 1>
Prepare the following timbers as treated timbers, load them on a pallet so that adjacent timbers do not come into contact with each other, bind them to a cart, and carry them into the pressure vessel of the timber processing device in FIG. Colored wood was produced under the following processing conditions. The colored wood in which cracks having a depth of 1 mm or more occurred was determined to be defective, the dry crack defect rate was determined from the number of defective products generated in 250 treated wood, and the results are shown in Table 1. Table 1 also shows the measurement results of the moisture content of the manufactured colored wood. In addition, the moisture content was calculated | required according to the following Formula by the test method (JISZ2101) of wood.
Moisture content [%] = (mass of wood before drying [g] −total dry mass [g]) / total dry mass [g] × 100
Here, the total dry mass is a mass when the wood before drying is dried at a temperature of 100 ° C. to 105 ° C. in a well-ventilated dryer and reaches a constant weight.
Moreover, assembling suitability and slicing suitability were evaluated as follows using the produced colored wood. The results are also shown in Table 1.

Wood tree species: Hippo lumber flitch Moisture content: 62-74%
Size: 40mm thick x 110mm wide x 650mm long
Treatment conditions / temperature increase, pressure increase process Steam deaeration (introduction of water vapor into the pressure vessel): 100 ° C., 3 minutes Temperature increase time: 30 minutes (temperature increased from normal temperature to 140 ° C.)
-Holding process Temperature, holding time: 140 degreeC, 2 hours, temperature fall, pressure-lowering process Wood was cooled by natural cooling, releasing the water vapor | steam in a pressure vessel over air | atmosphere over about 2 hours.
-First submersion step, first depressurization step Water injection was started when the atmospheric pressure of the pressure vessel dropped to 0.05 MPa or less, and the wood was submerged and cooled for 1 minute while circulating water. Then, it was drained, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the atmosphere was released after 3 minutes.
<Evaluation of assembly suitability>

The manufactured colored wood was precisely finished with a molder, the length was cut with a saw, and a combination of a plurality of moisture-curing urethane adhesives applied to the cut surfaces was bonded together to obtain a laminated material. The assembled flitches were processed into a 0.25 mm thick single plate with a slicer. If the obtained single plate was not scattered, it was rated as “◯”, and if there was a slight variation, it was marked as “△”, resulting in many variations. The thing was set as "x".
<Evaluation of slicing suitability>
The produced colored wood was processed into a 0.25 mm thick single plate with a slicer. If the obtained single plate was not cracked due to cracks, it was rated as “◯”, if slightly cracked, “Δ”, and if many cracks occurred, “x”.
<Example 2>

Example 1 is the same as Example 1 except that colored wood was produced under the following processing conditions. Table 1 shows the dry crack defect rate and moisture content of the manufactured colored wood. Table 1 also shows the evaluation results of the suitability for assembly and the suitability for slicing using the produced colored wood.
Treatment conditions / temperature increase, pressure increase process Steam deaeration (introduction of water vapor into the pressure vessel): 100 ° C., 3 minutes Temperature increase time: 30 minutes (temperature increased from normal temperature to 140 ° C.)
-Holding process Temperature and holding time: 140 degreeC, 2 hours and temperature fall, pressure-lowering process The water vapor | steam in a pressure vessel was open | released to air | atmosphere over about 2 hours, and wood was cooled by natural cooling. Thereafter, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the air was released to the atmosphere after 3 minutes.
-1st water immersion process, 1st pressure reduction process Water was poured into the pressure vessel and the wood was submerged and cooled. After submerging, the water was discharged, the atmospheric pressure in the pressure vessel was kept at −0.80 MPa, and the atmosphere was released after 3 minutes.
<Example 3>

  Example 1 is the same as Example 1 except that colored wood was produced under the following processing conditions. Table 1 shows the dry crack defect rate and moisture content of the manufactured colored wood. Table 1 also shows the evaluation results of the suitability for assembly and the suitability for slicing using the produced colored wood.

Treatment conditions / temperature increase, pressure increase process Steam deaeration (introduction of water vapor into the pressure vessel): 100 ° C., 3 minutes Temperature increase time: 30 minutes (temperature increased from normal temperature to 140 ° C.)
-Holding process Temperature and holding time: 140 degreeC, 2 hours and temperature fall, pressure-lowering process The water vapor | steam in a pressure vessel was open | released to air | atmosphere over about 2 hours, and wood was cooled by natural cooling. Thereafter, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the air was released to the atmosphere after 3 minutes.
-First submersion step, first depressurization step Water injection was started when the atmospheric pressure of the pressure vessel dropped to 0.05 MPa or less, and the wood was submerged and cooled for 1 minute while circulating water. Then, it was drained, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the atmosphere was released after 3 minutes.
-2nd water immersion process, 2nd pressure reduction process Water was poured into the pressure vessel and the wood was submerged and cooled. After submerging, the water was discharged, the atmospheric pressure in the pressure vessel was kept at −0.80 MPa, and the atmosphere was released after 3 minutes.
<Comparative Example 1>

Example 1 is the same as Example 1 except that colored wood was produced under the following processing conditions. Table 1 shows the dry crack defect rate and moisture content of the manufactured colored wood. Table 1 also shows the evaluation results of the suitability for assembly and the suitability for slicing using the produced colored wood.

Treatment conditions / temperature increase, pressure increase process Steam deaeration (introduction of water vapor into the pressure vessel): 100 ° C., 3 minutes Temperature increase time: 30 minutes (temperature increased from normal temperature to 140 ° C.)
-Holding process Temperature, holding time: 140 ° C, 2 hours-Submerged process, decompression process Water injection was started while maintaining the atmospheric pressure of the pressure vessel at a high pressure, and the wood was submerged and cooled in a high pressure state for 1 minute while circulating the water. . Then, it was drained, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the atmosphere was released after 3 minutes.
<Comparative example 2>

Example 1 is the same as Example 1 except that colored wood was produced under the following processing conditions. Table 1 shows the dry crack defect rate and moisture content of the manufactured colored wood. Table 1 also shows the evaluation results of the suitability for assembly and the suitability for slicing using the produced colored wood.
Treatment conditions / temperature increase, pressure increase process Steam deaeration (introduction of water vapor into the pressure vessel): 100 ° C., 3 minutes Temperature increase time: 30 minutes (temperature increased from normal temperature to 140 ° C.)
-Holding process Temperature, holding time: 140 degreeC, 2 hours, temperature fall, pressure reduction process The water vapor | steam in a pressure vessel was open | released to air | atmosphere over about 2 hours, and the wood was cooled by natural cooling. Thereafter, the atmospheric pressure in the pressure vessel was kept at -0.80 MPa, and the air was released to the atmosphere after 3 minutes.

  From the results in Table 1, it was confirmed that the colored wood produced in Example 1-3 had a low dry crack defect rate. In addition, it was confirmed that the colored wood was well assembled and sliced.

  The colored wood produced in Example 2 has a relatively low water content because it has been subjected to a decompression process before submerging the wood in the production process, and the colored wood produced in Example 1 is used. In comparison, the assembly suitability and slicing suitability are better.

  In the colored wood produced in Example 3, the submerged cooling of the wood and the subsequent decompression are repeated a plurality of times in the production process, so that the wood is effectively cooled and compared with the wood produced in Example 1-2. The dry crack defect rate is reduced.

On the other hand, the colored wood produced in Comparative Example 1 is submerged and cooled in a high-pressure state in the production process, so that the moisture content is high. Assembling suitability and slicing suitability using this colored wood are as in Example 1-. It is inferior to 3.
Moreover, since the colored wood manufactured in Comparative Example 2 is not submerged in the manufacturing process, the defective dry crack rate is higher than that in Example 1-3.

  20 wood

Claims (3)

A method for producing colored wood, comprising producing colored wood through the following steps in sequence.
Step A: Step of coloring the wood by high-pressure steam treatment under an atmospheric pressure higher than atmospheric pressure by raising the temperature of the sealed space containing the wood and increasing the pressure.
Step B: Step of reducing the atmospheric pressure of the sealed space,
Step C: introducing water into the sealed space before the temperature of the wood raised by the high-pressure steam treatment in Step A reaches room temperature, and submerging the wood in an atmospheric pressure atmosphere,
Process D: The process of draining the water of the said enclosed space, and reducing the atmospheric pressure of the said enclosed space to a pressure lower than atmospheric pressure.   The method for producing colored wood according to claim 1, wherein the step B reduces the atmospheric pressure of the sealed space to a pressure lower than atmospheric pressure.   The method for producing colored wood according to claim 1, wherein the step C and the subsequent step D are repeated a plurality of cycles as one cycle.

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