WO1991007261A1

WO1991007261A1 - Drying method for wood or the like

Info

Publication number: WO1991007261A1
Application number: PCT/JP1990/001473
Authority: WO
Inventors: Hideaki Takahashi; Kinji Tamakawa; Kiyoshi Sato; Isao Suzuki; Satoshi Yunome; Katsumi Honma; Yasuo Suzuki
Original assignee: Miyagiken; Kyogyokumiai Sendai Fanichia
Priority date: 1989-11-13
Filing date: 1990-11-13
Publication date: 1991-05-30
Also published as: JP2779962B2; JPH03156281A

Abstract

This invention relates to a drying method for wood and the like which comprises conducting impregnation treatment by allowing a plant manufactured lumber to be impregnated with an organic impregnant and subjected to a hydrothermal reaction (hydrolysis), fitting an acoustic emission sensor to the lumber or the like thus subjected to the impregnation treatment, detecting an acoustic emission which the lumber or the like generates with the change of their wood structure as a signal, forecasting cracks in the lumber or the like by data-processing the signal and carrying out heat treatment while controlling the atmosphere using temperature and humidity as operation factors on the basis of the forecast data so that no cracks occur in the lumber or the like. The present invention relates also to a drying method of lumber or the like which is characterized in that heating and drying are carried out after the lumber or the like is impregnation treated with an organic impregnant.

Description

Saying Moon Itoda »

Drying method for wood etc.

Technical field

The present invention relates to a method for heat-drying various plant-based processed materials (hereinafter, referred to as “wood and the like”) such as logs, processed wood, and bamboo so as not to cause cracking. Background art

Wood is usually dried to prevent it from becoming messed up when used, and to improve workability, paintability and adhesion. This drying method can be roughly classified into two types: natural drying and artificial drying. In recent years, there has been a demand for a large amount of drying treatment in a short period of time, uniform drying to a low moisture content, which is difficult to obtain with natural drying, etc. In most cases, the artificial drying method is adopted.

The most important issue in such a wood drying process is to avoid cracking. In particular, in the case of the so-called artificial drying method in which the heat drying treatment is forcibly performed, cracks are likely to occur as the drying conditions are severe. If cracking occurs, the quality will be extremely deteriorated or the product value will be lost, and if you take long days carefully so as not to crack, the processing efficiency will be too bad, It is not a feasible business.

For this reason, techniques for shortening the drying time while preventing cracking in wood drying treatment have been studied in various fields, but no definitive method has yet been developed.

Therefore, while investigating the causes of cracks in wood and other materials during heat treatment and studying ways to prevent them, cracking due to drying is a type of solid destruction. (Hereinafter, referred to as AE). We have begun research on techniques for detecting cracks by observing them and predicting cracks due to drying. At the same time, we investigated the technical literature on the relationship between cracking and the AE of wood, and noticed that there was a well-known technology called “a device for predicting and preventing dry cracking of wood” (Japanese Patent Publication No. 63-73117). Was.

Also, I recently learned that wood can be converted into a material with the same plasticity as plastic by a simple chemical reaction.

The present inventors have conducted research with the hints as a hint to prevent cracks in the drying treatment of wood and the like, and have completed the present invention. The causes of cracks in wood, etc. when heat-treated wood, etc., can be broadly attributed to water movement during the heating and drying process and tissue shrinkage. First, the following facts were found regarding cracking of wood and other materials due to moisture movement and tissue shrinkage during the drying process. The water contained in wood usually includes free water and bound water, but during drying, only free water is first eliminated and removed from the surface layer, and then the bound water is removed as drying progresses become. The movement of free water in the former is dominated by capillary action, and the movement of bound water in the latter is by diffusion. In this way, the free and bound water of the surface layer of the wood migrates and dries, but the inner layer still has a high moisture content. The dry area then tries to shrink, and the wet areas resist shrinkage. As a result, in the first half of drying, tensile stress acts on the surface layer and compressive stress acts on the inner layer. Furthermore, as the drying proceeds, these stresses increase and the shrinkage also spreads inward, but the surface layer is constantly subjected to a large tensile stress, so that permanent deformation occurs without regular shrinkage. After that, as the inside dries, the surface layer tries to shrink normally, and the positive and negative stresses are reversed. In the latter half, the surface layer receives compressive stress and the inner layer receives tensile stress. For this reason, if the tensile stress exceeds the tensile strength of the wooden part, cracks in the mouth or surface cracks along the surface fibers occur in the first half of drying, and internal cracks occur in the second half of drying. In addition, surface hardening and drying Defects called creaking also occur, but it was also found that these were all directly related to the magnitude of the gradient of the water content distribution inside the wood. In heating and drying, it is required that the above-mentioned various cracks and other defects do not occur, and that the drying time be shortened by increasing the gradient of the water content distribution inside the wood as much as possible. For this purpose, it is important to grasp the distribution of moisture content in the wood from time to time, and it is necessary to dry the wood while adjusting the temperature and humidity according to the moisture content of the wood during drying. However, since the wood structure is complicated and the thermal properties are affected by humidity and moisture content, and also differ depending on the wood species, it is theoretically necessary to grasp the momentary water content distribution inside the wood. Is difficult. In addition, since the mechanical strength and thickness of the material are also involved in the occurrence of cracks caused by drying, it is necessary to clarify under what conditions defects occur in complex wood structures with large anisotropy. Is extremely difficult.

Therefore, in the conventional drying process, it is the current practice to enter the room during drying, check for cracks visually, and readjust the atmosphere in the room. However, this method cannot predict before cracks occur and cannot find cracks that occur inside.

Therefore, the present inventors use a known technique (for example, Japanese Patent Publication No. 63-7311) to predict the dry cracking of wood using AE detection technology and control the temperature and humidity around the wood to prevent cracking. We focused on 7). However, the known literature only describes that the initial cracks in the drying treatment are predicted based on the AE accumulation number and the AE occurrence rate. In other words, even in the case of the drying treatment, it is a prediction of the initial crack of the drying, and the crack in the later stage of the drying treatment is not recalled. In addition, the method of predicting initial cracking is only to know the cumulative number of AEs and the AE occurrence rate immediately before the cracking of the wood, and when the AE occurrence rate reaches the limit value, actuate the control equipment to relax the drying conditions and prevent cracking. It is.

According to this conventional technology, the correlation between the cumulative number of AEs and the It can be used to some extent in early drying cracks, but it does not necessarily show a correlation in the middle and late drying stages. It turns out that there are defects such as,. The inventor observed and analyzed the occurrence of AE signals and cracks in the wood, and noticed that cracks in the wood had a close correlation with the amplitude of the AE signal. Attention should be paid to discriminate and detect effective signals directly linked to cracking.If even one AE signal has a large amplitude, it is considered a danger signal for cracking, and the cumulative number of AE events and the AE occurrence rate with a large amplitude are online. While monitoring with a computer, it is always possible to identify whether the dry state is in the initial, middle or late stages, and make a comprehensive judgment by comparing with the reference values set in advance in each of the identified processing stages. In order to predict cracks during the treatment process. Then, based on the prediction information obtained in this way, the temperature and humidity are manipulated to control the atmosphere so that cracks do not occur in wood and the like.

Wood impregnation technology is widely used, but there is no known example of using an impregnating agent in advance to prevent cracking during drying or heat treatment. The inventor has reported that when a specific organic solvent is impregnated into wood or the like from among various impregnating agents and then heat-treated, a chemical reaction occurs inside and plasticization occurs internally, giving the material heat fluidity. The inventor of the present invention has obtained the knowledge and thought that if this knowledge is applied, it may be possible to prevent cracking due to heat fluidization inside wood during heat treatment. That is, by impregnating with a specific organic solvent and performing a hydrothermal chemical reaction, the interior of the wood is plasticized. With this, it is intended to prevent cracking even if artificial drying is performed under severe heat treatment conditions. Disclosure of the invention

The invention of the present application is a technique for preventing cracking during the drying process as described above. The technical problem is solved by combining the following technical means.

The inventor of the present invention has studied cracks caused by heat drying of wood and the like, and has found that the cracks are caused by moisture movement, tissue shrinkage, and decomposition of cellulose by high heat. Also, dry cracking of wood is one of the forms of solid destruction, and it is thought that acoustic emission (AE) should occur, and this is detected and its frequency and signal are detected. We thought that if we could know the strength, we could process this information and predict cracks in advance. As a result of the research, we noticed that wood cracking has a close correlation with the amplitude of the AE signal as well as the amplitude of the AE signal. Detected by discrimination. As a result, if the amplitude of even a single AE signal was large, it could be understood as a danger signal for cracking. In addition, online monitoring of the number of accumulated AE events and the AE occurrence rate of the amplitude that is effective in predicting this crack is used to identify whether the dry state is in the initial, middle, or late stages. The meaning of the detected AE signal is analyzed and examined by comparing it with the empirically predetermined reference value in the processing stage to predict and judge cracking during the processing process, and the temperature, humidity and By manipulating the atmosphere, the atmospheric conditions are controlled so that cracks do not occur in the wood and the like. Cracks in wood and the like are caused by the movement of moisture during drying and heat treatment and the denaturation of the material due to heat.It was found that cracking can be sufficiently prevented by adjusting temperature and humidity as operating factors. .

Furthermore, prior to the drying treatment, the organic impregnating agent is impregnated in advance, and if this is put into high-temperature water of 100 ° C or less, the wood part becomes thermoplastic (thermofluidity) due to hydrothermal chemical reaction (hydrolysis) No chemical cracking occurs even in the heat-drying process because the material is deformed corresponding to the difference in tensile stress and compressive stress between the surface layer and the inner layer caused by heating. It was found that the wood part chemically changed into a state of thermoplasticity (thermofluidity) by the impregnation with the organic impregnating agent.

So, these three ideas:

First, to prevent dry cracking by chemically converting wood into wood by impregnation with an organic impregnating agent;

Second, detecting the A / E signal and predicting cracks in wood and the like by its information processing;

Third, to prevent cracking by controlling the atmosphere using temperature and humidity as operating factors based on the prediction information.

By combining the above as appropriate, it is intended to efficiently dry wood, etc., and to process and provide a large amount of uniformly dried wood. Hereinafter, the invention for which a patent is sought will be described in detail.

The first invention for which a patent is sought is, first, various kinds of processed plant materials such as logs, processed wood, bamboo, etc. (wood, etc.), oxyethers such as polyethylene glycol and methylcellulose sorb, and polyvalent. It is impregnated with an organic impregnating agent such as alcohols, phenols, natural rubber or synthetic rubber, or a combination of these, and undergoes a hydrothermal chemical reaction (hydrolysis).

The processing range of the present invention is wood and the like, which includes all kinds of plant-processed materials such as logs, processed wood, and bamboo regardless of the type of plant.

Specific organic impregnants to be impregnated include oxyethers such as polyethylene glycol and methyl sorb, polyhydric alcohols such as 1,4-butanediol, phenols such as phenol, natural rubber and synthetic rubber. Any material can be used as long as it relates to rubber or a combination thereof.

Next, the change in wood quality caused by the impregnation process will be described.

Chemically, wood is a 40-50% amount of cellulose, 15- Consists of 25% hemicellulose, 20-30% lignin and other minor components. In addition, in the cell wall constituting wood, a bundle of cellulosic molecular chains passes through a sponge-like network, and the components are combined in such a way that the gap between the two is filled with hemicellulose. Have been done. Further, the bundle of the aggregate of the cellulose molecular chains is regularly arranged to form crystals. This is a linear macromolecule with a regular configuration, which has a large number of hydroxyl groups (1OH), so that regular hydrogen bonds between hydroxyl groups are likely to occur between adjacent molecules. Moreover, this accounts for 70% of the total cellulose. This cellulose has a high melting temperature of the crystals, and even if heated, it undergoes thermal decomposition before flowing, so that it does not eventually flow. It is considered that such properties of wood and the like facilitate cracking due to water movement, tissue shrinkage, and thermal decomposition of cellulose. However, if chemical modification is performed to replace the hydroxyl group (-1 OH) of cellulose with an acetyl group (-1 C 0 CH ₃ ), nitro group, benzyl group, lauroyl group, etc., internal plasticization occurs in wood, resulting in thermal fluidization. Gender. In other words, it was thought that cellulose would be converted to a derivative, and the degree of hydrogen bonding would be reduced, resulting in a material with thermal fluidity in timber. As described above, if the cellulose crystals are caused to flow, even if they are heated and dried under quite severe conditions, shrinkage cracks and moisture transfer cracks do not occur.

As a specific method, he recalled using the fact that wood becomes thermo-fluid (thermoplastic) due to hydrothermal chemical reaction. In other words, as a pretreatment step, the raw wood is impregnated with a specific organic impregnating agent, and this is placed in high-temperature water of 100 ^eC or less to cause a hydrothermal chemical reaction (hydrolysis). Dissolves some of the cellulose and lignin in wood to partially cleave some chemical bonds, alcoholizes esters in resins, and halogenates lignin aromatic nuclei to lignin chloride The state where the wood part has thermo-fluidity (thermoplasticity) It was in a state.

Next, an AE sensor is attached to the impregnated wood, etc., and the AE generated by the wood, etc. accompanying the change in the wood structure is detected as a signal, and the signal is processed to predict cracking of the wood, etc. while cracking wood or the like is so controlled atmosphere so as not to cause the base Hazuki temperature and humidity prediction information as the operation factors performed 1 0 0 ^e C following heat treatment at atmospheric pressure makes the drying process.

A Attach the E-sensor through the wave guide considering the temperature and humidity. The mounting position of the wave guide was at the tip of the test piece.

Then, the AE generated by the change in the structure of the wood is detected as an electrical signal, and the information is analyzed to predict cracks in the wood.

As described above, even in the drying process, the progress of the drying of wood or the like can be always grasped by observing the AE signal.

The signal sent from a sensor attached to wood, etc. is amplified by a preamplifier, and the signal below the set value is cut by a cracking monitor.After amplification, an AE event with a specific amplitude is detected, and this specific amplitude AE event data Is recorded (Fig. 14). Fig. 15 shows this as the cumulative AE energy. If a large number of cases are collected through such experiments and statistically processed, a standard AE pattern in the wood drying process as shown in Fig. 3 can be obtained.

Based on the standard AE pattern in this drying process, the following empirical rules for predicting cracks in wood and the like were obtained.

(1) If an AE signal with a certain amplitude or more that is empirically determined appears, it is considered as a precursor to cracking.

(2) There are three stages in the drying process: early, middle and late. It is important to change the judgment standards for each stage. The first stage (I) is considered to be a stage in which steam penetrates to the center of wood and the like, and the temperature and moisture content are made uniform, and drying proceeds gradually. The water content in the first and second stages is 25%, which corresponds to the fiber saturation point (about 30 to 25%). Above the fiber saturation point, there is liquid water in the wood. Care must be taken at this stage as cracks can easily occur.

The second stage (Π) is considered to be the stage in which the absorbed water force, in the form of bound water in the fiber, breaks the bond and begins to evaporate. Therefore, the energy required to lower the water content is higher than in the first stage. At this stage, the tensile strength of the timber will increase sharply and it will be possible to end the harsh drying conditions from the first stage. Therefore, stricter drying conditions can be provided than in the first stage. In other words, in the second stage, severe drying conditions are applied, thereby shortening the drying time. The boundary between the second and third stages corresponds to a water content of about 15%. This water content of about 15% is considered to correspond to the equilibrium water content, and corresponds to the air-dry state.

In the third stage, there are many small-amplitude AEs, so it is considered that the hydration ^s inside the cells and the detachment from the cells decrease. However, since this small amplitude AE has nothing to do with dry cracking, drying conditions can be set regardless of the number of AE events. Therefore, in the third stage, it is possible to set more strict drying conditions than in the second stage, and here it is possible to further shorten the drying time. In this way, when the drying state progresses and the water content falls below 10%, the AE with small amplitude also decreases.

Therefore, the method of predicting “cracking” in the drying process is to identify which drying stage is currently in progress while monitoring the AE occurrence rate and the cumulative number of AE events of a specific amplitude online. At the same time, it predicts cracking during the treatment process by comparing it with the standard AE occurrence situation (the AE occurrence rate and the cumulative number of AE events) determined empirically and the crack warning standard value. You.

Next, the temperature condition and the humidity condition were manipulated based on the optimal control pattern at that stage empirically determined based on the crack prediction information to relax the atmospheric conditions so that cracks did not occur in wood and the like. Control and strict temperature and humidity conditions to avoid loss of processing efficiency. In this way, cracks are predicted by analysis of the AE signal, and drying is performed while controlling the atmosphere using temperature and humidity as operating factors, until the moisture content of wood and the like becomes 10% or less.

That is, in the present invention, first, impregnation processing is performed, and AE is predicted based on a signal based on a signal to detect cracks in wood, and the atmosphere is controlled based on the prediction information so that cracks do not occur in wood and the like using temperature and humidity as operating factors. Drying is performed while drying.

FIG. 1 is a flowchart of the drying control when the drying process is performed while controlling the atmosphere, and FIG. 2 is a standard AE when the temperature and the humidity are controlled in the drying process. This is a schematic diagram of the occurrence pattern.

The second invention for which a patent is sought is that wood or the like, oxyethers such as polyethylene glycol / methyl sorbate, polyhydric alcohols, phenols, natural rubber or synthetic rubber, or an organic compound obtained by combining these. This is a method for drying wood and the like, characterized by impregnating with an impregnating agent and performing a hydrothermal chemical reaction (hydrolysis), followed by heating and drying.

In the present invention, as in the first invention, the raw wood is impregnated with a specific organic impregnating agent, thereby converting cellulose into a derivative and reducing the degree of hydrogen bonding. It will be fluid. As described above, when the cellulose crystals are caused to flow, even if they are heated and dried under quite severe conditions, shrinkage cracks and moisture transfer cracks do not occur. Based on this principle, it is a method for drying wood and other materials that does not crack even when heated and dried. As a specific method, wood is made to have a thermofluidity (thermoplasticity) by a hydrothermal chemical reaction. That is, prior to the processing steps, is impregnated with the specific organic impregnant material timber causes which put in hot water of 1 0 0 ^e C hereinafter undergo hydrothermal chemical reaction (hydrolysis), in the wood Dissolve a part of the cellulose lignin, etc., in order to partially cleave some chemical bonds, alcoholize the esters in the resins, halogenate the lignin aromatic nucleus to make lignin chloride, etc. Then, the wood part is in a state of having thermo-fluidity (thermoplasticity).

In the present invention, if the impregnation treatment is performed in this manner, the heating and drying treatment method is not particularly limited, and the heating and drying cracks do not occur in most cases under the conventionally performed heating and drying conditions. Of course, and individual characteristics of the processed wood, by special heating conditions, but there is no high-end and no case of break, for example, according to Example 1., No longer be said conventional drying processing 1 5 O ^e Even in the case of increasing the degree of drying by heating to a high temperature of about C (it is necessary to set a nonflammable atmosphere as necessary), there was almost no cracking. (Fig. 4, Fig. 6, Fig. 8, Fig. 10) Therefore, general drying performed at a standard heating and drying temperature (30 to 100 ° C) with mild heating conditions If processing, this will not cause cracking. In other words, as long as the impregnation treatment is performed as the pretreatment, cracking during the drying treatment can be reduced at least dramatically as long as the drying treatment is performed under conventional common-sense heating conditions. In the third invention to be patented, an AE sensor is attached to wood, etc., and the AE generated by the wood, etc. due to a change in the structure of the wood is detected as a signal, and the amplitude of the signal is discriminated to a predetermined value. The AE signal with the above amplitude is regarded as a danger signal for cracking, and furthermore, while monitoring the cumulative number of AE events and the AE occurrence rate online, it is always possible to identify whether the dry state is in the initial, middle or late stages. While the pre-set cumulative AE event for each identified processing step The number of AEs and the reference value of the AE occurrence rate are compared with the reference value of the crack warning, and the crack is predicted, and the temperature condition is determined based on the optimal control pattern at that stage empirically determined based on the prediction information. This is a method for drying wood and the like, characterized in that the atmosphere is controlled so that cracks do not occur in the wood and the like by manipulating the temperature and humidity conditions.

According to the present invention, in the drying process of wood, an AE signal is obtained, cracks are predicted by analyzing the AE signals, and the temperature and humidity are used as operating factors based on the crack prediction information, and the drying process is performed while controlling the atmosphere. In order to minimize dry cracking.

That is, the working steps characteristic of the wood drying method of the present invention are as follows.

(1) An A / E sensor is attached to wood, etc., and the detected A / E signal is focused on its amplitude, and only specific signals that are effective for crack prediction are discriminated and extracted. The specific method of attaching the AE sensor and the method of recording the AE signal are the same as those described in the first invention.

(2) Based on the selected specific amplitude AE signal, the cumulative number of AE events and the AE occurrence rate are processed and monitored to recognize the progress of drying in real time, and the dry state is in the early, middle, and late stages. Identify the stage of the

There are three stages in the drying process, and it is important to change the criteria for each stage.

③ Predict and judge cracking by comparing the preset number of accumulated AE events and the standard value of the AE occurrence rate with the standard value of the crack warning level at each processing stage identified from the real-time AE occurrence information. Figure 3 shows the standardized temperature and moisture content during wood drying treatment, the cumulative AE energy at that time, and the model pattern of the AE generation rate.

木材 Temperature and humidity conditions are manipulated based on crack prediction information and operating conditions based on the optimal control pattern determined at that stage. Atmosphere is controlled so that cracks do not occur.

FIG. 1 is a flowchart of the drying control when the drying process is performed while controlling the atmosphere, and FIG. 2 is a standard AE when the temperature and the humidity are controlled in the drying process. It is a schematic drawing of the occurrence pattern.

Moreover, from the results of many experiments, it was found that the following should be considered when examining the optimal work process in the above wood drying.

①Drying must be considered in three stages.

(2) In the first stage, a sufficient amount of steam is required.

At this stage, sufficient steam is used because cracks are likely to occur, and care should be taken to obtain a uniform moisture content and temperature distribution inside the wood. Cracking is very sensitive to changes in drying conditions, so it is necessary to gradually perform drying when strict drying conditions are used.

If AE indicates a sign of cracking, introduction of a large amount of steam is effective.

(3) In the second stage, it is possible to make the drying conditions stricter at high temperature and low humidity compared to the first stage. Therefore, it is possible to further accelerate the drying speed.

(4) In the third stage, more severe drying conditions are possible than in the second stage, and even if severe, cracks are unlikely to occur. Therefore, this step can minimize the drying time.

Considering the fact that the drying process differs in each stage as described above, the most efficient drying schedule is as follows.

Crack detection was performed with an AE measuring device, and the measurement system used in this experiment captured signs of cracking with the total number of AE events of 0.5 V or more, and dried so that this total number did not exceed a certain value. Control conditions. Drying conditions are basically controlled by temperature and relative humidity. The first, second and third steps are distinguished by the rate of increase of the cumulative AE energy. The specific control method is as shown in the flow chart of the drying control shown in FIG. Set the steam amount that is considered to be almost appropriate, and start drying at the expected temperature. When the number of AE events of 0.5 V or more per minute exceeds a certain value Nc (for each Z), temporarily inject a large amount of steam to prevent cracking, and at the same time set the temperature with AT dl Lower. If the number of A events at 0.5 V or more is N 0 or less for a certain period of time (about 10 minutes), raise the temperature set value by ΔT ul ° C to tighten the drying conditions. By this repetition, the temperature settles to a constant value (T c). However, the upper temperature limit for drying wood is empirically dependent on the species. If the temperature is too low, the drying efficiency will decrease. As described above, when Tc is not in the desired temperature range, the amount of steam is adjusted to control so that Tc falls within an appropriate temperature range. If it is determined from the increase rate of the accumulated AE energy that the process has shifted to the second stage, ΔT u2 and ΔT d2, which are different from the first stage, are used to control the temperature rise and fall. Here, ΔΤ ιιΙ <ΔT u2, and control is performed as in the first stage. Furthermore, if it can be determined from the third stage and the increase rate of the accumulated AE energy ^, control is performed using the temperature control parameters ATu3 and Td3. It is expected that ΔΤ ιι2 <ΔT u3, and the drying conditions will be more severe than in the second stage. The temperature control parameters ΔT ul, ΔT d1, ΔT u2, ΔT d2, Δ Τ u3, and Δ Τ d3 need to be determined for each tree species.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a flow chart of a drying control in the case where the drying process is performed while controlling the atmosphere using the AE according to the first and third inventions of the present application, and FIG. 2 is a diagram showing the temperature and humidity control in the drying process. Fig. 3 is a schematic diagram of AE generation, Fig. 3 is an AE generation model pattern during wood heating and drying, Fig. 4 is a graph recording the temperature change of the high temperature heating in Example 1, and Fig. 5 is Fig. 6 is a graph showing the number of AE events (occurrence rate) for each amplitude class of untreated wood in Example 1. Fig. 6 shows the number of AE events (occurrence rate) for each amplitude class of impregnated wood in Example 1. Fig. 7 is a graph that records the AE generation rate of the untreated material of Example 1 with an amplitude of 1 V or more, and Fig. 8 is the graph that records the AE of the impregnated material of Example 1 with an amplitude of 1 V or more. Fig. 9 shows the cumulative AE energy of the untreated material of Example 1 with an amplitude of 1 V or more. Fig. 10 is a graph in which the accumulated AE energy of the impregnated material of Example 1 with an amplitude of 1 V or more was recorded, and Fig. 11 is an AE generation during the high-temperature heat treatment of Example 1. Fig. 12 is a graph showing the crack limit control criterion based on the model pattern and the cumulative AE. Fig. 14 is a graph that records the number of AE events (occurrence rate) for each amplitude class of the treated material. Fig. 14 is a graph that records the temperature of the drying process and the AE occurrence rate with an amplitude of 1 V or more in Example 2. FIG. 15 is a graph in which the accumulated AE energy with an amplitude of 1 V or more in the drying treatment in Example 2 is recorded. FIG. 16 shows the change in the water content and the change in weight in the drying treatment in Example 2. BEST MODE FOR CARRYING OUT THE INVENTION

Prepare a maple natural wood log material (length 20 O mm X diameter 80) that has been naturally dried (water content 30%), decompressed at room temperature first, and degassed the wood. And then pressurize the resin liquid polyethylene glycol with a pressure pump. At 3-5 atm. Thereafter, the impregnated wood is placed in high-temperature water of 100 ° C. or lower to cause a hydrothermal chemical reaction. The log material thus pre-treated and the same log material without pre-treatment were placed in a heat treatment room, and an AE sensor was attached to these materials via a wave guide. Specifically, the terminal of the wave guide inside the heat treatment chamber is fixed to the test opening with a wood screw, and the wave guide is extended outside through the measurement hole provided in the heat treatment chamber. An AE sensor was attached to the camera, and it was connected to a preamplifier, cracking monitor, and personal computer located nearby. Next, air is degassed from the heat treatment chamber and nitrogen gas is injected from the non-flammable gas injection part to make a 97% non-flammable gas atmosphere. Then, while operating the thermocouple in the heating section to raise the temperature inside the heat treatment chamber, steam is injected from the steam injection section to adjust the internal humidity. As shown in Figure 4, is raised to stretch 1 5 0 ^e C, heated at a high temperature of 2 2 hours Hopo 1 5 0~ 1 6 0 ° C , about lowered then the temperature to room temperature in about 2 hours Processing was completed in 24 hours. During this time, we observed the occurrence of AE. Fig. 5 shows the AE event status for each amplitude class of unimpregnated treated material at that time. Fig. 6 is a record showing the AE event occurrence status for each amplitude of the impregnated material. Since it is not possible to identify at which point the cracks occurred in these figures, an AE with an amplitude of 1 V or more was specified and recorded with an amplification factor of 80 dB within one minute. The situation is shown in Fig. 7, and the occurrence of AE events in the impregnated material is shown in Fig. 8. The AE signal related to cracking can be recognized quite clearly. According to this report, both the untreated material and the impregnated material generate a large amount of AE in the early stage when the temperature in the heat treatment chamber rises, and almost no AE is generated in the intermediate stage, and the temperature decreases. At the beginning, AE events tend to occur again. However, the state of occurrence is quite different between the untreated material and the impregnated material, and the impregnated material is in a state where almost no AE is generated. In other words, the untreated material cracked at the early stage of heating The force impregnated material clearly shows that it did not crack. This can be more clearly recognized by comparing Fig. 9 (untreated material) and Fig. 10 (impregnated material) showing the accumulated AE energy.

Therefore, when heating wood at a high temperature so that it is not easily cracked like untreated wood, it is necessary to predict cracking and control the atmosphere. Fig. 11 shows the control model. That is, AE is detected as an electrical signal, and this data is recorded and analyzed by a personal computer, and information processing is performed. Cracks in wood and the like are predicted by comparing them with reference values that are set empirically in advance. For example, if an AE with an amplitude of 1 V or more was recorded within one minute with an amplification factor of 80 dB, and the cumulative number of events exceeded the reference value or the amplitude exceeded the reference value, it was said that a crack warning area was reached. Judging, the steam injection unit is activated to inject a large amount of steam into the heat treatment room in a short time, and the humidity in the heat treatment room is adjusted, and the operation of the heating unit is controlled to control the inside of the heat treatment room (heat treatment room). The temperature is adjusted to control the atmosphere so that no AE is generated from wood, etc., or the AE signal is maintained at a level below a predetermined standard, and the heating unit is operated while controlling such atmosphere As a result, the temperature in the heat treatment room was gradually increased, and high-temperature heating and drying without cracks in wood and the like was realized.

As a result, the impregnated high-temperature heat-dried material had a dryness of about 2% and had no cracks, whereas the non-impregnated high-temperature heat-treated material had many radial cracks. Example 2>

A piece of rice hiba wood, 493 x 101 x 3 Omm, was raised to 55 ° C at a stretch, heated and dried at 55 to 65 ° C for 105 hours, and then heated. The temperature was lowered to room temperature to complete the process (Fig. 12). During this time, we observed the occurrence of AE. Fig. 13 shows the AE event status for each amplitude class of untreated material at that time. As a result, it was dried from a water content of 45.5% to 13.2% (Fig. 16). No cracks were observed during this drying treatment.

As shown in FIG. 12, the drying treatment conditions in the present embodiment become stricter in the latter half of drying. The number of AE events shows a sharp increase after 100 hours (Figs. 14 and 15). However, when classified by level, they are as shown in Fig. 13, and when an AE of 0.5 V or more is applied, they are reduced as shown in Fig. 14. Therefore, it is considered that the AE signal of 0.5 V or less does not contribute to the occurrence of cracks. From the following graphs, it can be seen that the drying conditions may be stricter in the latter half of drying, but it is not clear from which point the latter half is indicated.

However, as shown in Fig. 15, drying can be divided into three stages in terms of the accumulated AE energy. In other words, from Fig. 15 showing the cumulative AE energy, the gradient of the cumulative AE energy clearly changes in about 45 hours and about 95 hours, so the first stage is up to 45 hours and from 45 to 95 hours. Can be classified as the second stage, and after 95 hours as the third stage.

As described above, in wood drying, it is important to analyze the AE signal to understand the drying stage, and by setting the drying conditions according to each stage, it is possible to dry so as not to crack and dry. The period can be shortened. Industrial applicability

The first invention of the present application is to impregnate wood or the like with a specific organic impregnating material, and to perform a hydrothermal chemical reaction (hydrolysis), and then heat and dry the impregnated wood or the like. During heating and drying treatment, wood and other materials are detected as acoustic emission generated by the change in the structure of the wood as a signal to predict cracking of the wood, etc., and cracks occur in the wood and the like using temperature and humidity as operating factors. This is a method for drying wood and the like, in which the drying process is performed while controlling the atmosphere so that there is no drying. By impregnating the organic impregnant, wood can be made thermoplastic, and during heat drying, AE is used as a signal and temperature and humidity are used as operating factors to control the atmosphere. By doing so, cracking during processing can be almost completely prevented even when processing raw wood with a high moisture content, and efficient drying can be performed with the processing time reduced as much as possible. Became. As a result, we were able to overcome the conflicting technical demands of preventing the yield from lowering in the conventional drying process and short-time drying process.

The second invention of the present application is a wood drying method in which wood or the like is impregnated with a specific organic impregnating material, subjected to a hydrothermal chemical reaction (hydrolysis), and then heated and dried. The heating and drying treatment here is not particularly limited as long as it is a conventional general heating and drying treatment method. It is not always necessary to detect the AE signal and grasp the dry state in real time.

Wood is plasticized by impregnation, so that even if the wood layer shrinks or is pulled by heating, it deforms in response to the stress and prevents cracking. For this reason, cracking does not occur in most cases if the conventional general heat drying treatment method is adopted. In other words, although the crack prevention rate is not as reliable as the first invention, the cracks in the drying treatment can be prevented with much higher probability than the conventional drying method.

The third invention of the present application does not perform impregnation processing, but performs heat drying processing while detecting and analyzing AE as a signal in the drying step, predicting cracks, controlling the atmosphere, and preventing cracks. This has made it possible to industrially and efficiently mass-produce high-yield, crack-free, high-quality dry wood with good yield.

Claims

The scope of the claims

1. Various kinds of plant-based processed materials such as logs, processed wood, bamboo, etc. (hereinafter referred to as “wood, etc.”), oxyethers such as polyethylene glycol and methyl sorb, polyhydric alcohols, phenols, natural rubber or natural rubber. Impregnated with an organic impregnant for synthetic rubbers or a combination of these, and subjected to hydrothermal reaction (hydrolysis),

An acoustic emission sensor is attached to the impregnated wood, etc., and the wood, etc. detects the acoustic emission generated as a result of the change in the structure of the wood as a signal, and processes the signal to process cracks in the wood, etc. The temperature and humidity are used as operating factors based on the prediction information, and the following heat treatment is performed at 100 at normal pressure while controlling the atmosphere so that cracks do not occur in wood and the like. Method for drying wood.

2. Impregnate wood or the like with an organic impregnating agent such as polyethylene glycol-methyl sorbate, etc., polyhydric alcohols, phenols, natural rubber or synthetic rubber, or a combination of these to hydrothermally. A method for drying wood or the like, characterized in that it is impregnated with a chemical reaction (hydrolysis) and then heated and dried.

3. Attach an acoustic emission sensor to the wood, etc., detect the acoustic emission generated by the timber, etc. as the wood structure changes, and discriminate the amplitude of the signal to determine The acoustic emission signal with the above amplitude is used as a danger signal for cracking, and the number of accumulated acoustic emission events and the incidence of acoustic emission are monitored online. While identifying the initial, middle, and late stages of the dry state, the number of accumulated acoustic emission events and acoustics that have been set empirically in each of the identified processing stages is determined. Predicting cracking during the treatment process by comparing the standard value of the stick emission rate and the crack warning standard value, and based on the optimal control pattern at that stage determined empirically based on the prediction information, A method for drying wood and the like, characterized by controlling the atmosphere so that cracks do not occur in the wood and the like by manipulating temperature and humidity conditions.