Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Wood Society  

DOI： 10.2488/jwrs.64.87

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DOI： 10.2488/jwrs.64.72

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DOI： 10.2488/jwrs.63.277

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The effects of climate change on the reduction of internal bond strength (IB) of particleboard subjected to various climatic conditions in Japan were predicted. The temperature increased throughout Japan with increasing greenhouse gas (GHG) emissions, so the climate deterioration index (climate index for predicting the IB reduction of particleboard; a high index indicates a large IB reduction) also increased to decrease IB. The number of low-temperature areas decreased because of climate change. The rupture of bonding points in particleboard caused by outdoor exposure led to a IB reduction, and biodeterioration accelerated this reduction. In high-temperature areas, particleboard was found to be prone to biodeterioration, and the IB significantly reduced. An area wherein there was a significant decrease in the IB spread along the Pacific Ocean side of western Japan and the Sea of Japan in central Japan in relation to increasing GHG emissions. Particleboards are difficult to use outdoors because of climate change.

DOI： 10.1007/s10086-017-1622-7

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Particleboard specimens were subjected to various climatic conditions in Japan, and the relationships between climatic factors and internal bond strength (IB) were investigated using multiple regression analysis (MRA) or artificial neural networks (ANN). At low- and middle-temperature sites, the IB predicted using MRA (IBMRA) and ANN (IBANN) decreased linearly with increasing exposure time. In addition, at high-temperature sites, with increasing exposure time, IBMRA decreased linearly, whereas IBANN decreased exponentially. The trend of IBANN was almost identical to that of the measured IB of the specimens subjected to various climatic conditions. Moreover, IBMRA and IBANN for 1-, 3-, and 5-year exposures were predicted using nationwide climatic factors. The minimum IB is zero when the particleboard is deteriorated; however, negative IB was predicted using MRA when the exposure time increased in the high-temperature area. In addition, the IB for 1-year exposure in the low-temperature area near site 1 was higher than the initial IB of 0.833 MPa. MRA is not always valid because of the assumption of linearity. However, negative IB even for 5-year exposure in the high-temperature area and high IB even for 1-year exposure in the low-temperature area were not predicted using ANN. The IB reduction was predicted correctly using ANN, and the correct IB reduction could be mapped.

DOI： 10.1007/s00107-016-1056-8

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Wood Society  

DOI： 10.2488/jwrs.63.63

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

The relationship between climatic factors and strength reduction of particleboard subjected to various climatic conditions at eight sites in Japan was investigated. Climatic factors such as mean temperature, sunshine duration, and precipitation were analyzed by principal component analysis. The first principal component score was introduced as a climate deterioration index (CDI). The particleboard strength reduced in high-CDI area. In this useful index for mapping deterioration zones, the CDI distribution was mapped. The strength reduction was predicted with multiple regression analysis using the CDI and exposure time, and the distribution of strength reduction after the outdoor exposure test was mapped as well. Strength reduced significantly in the southern area, particularly along the Pacific Ocean coast. The high-CDI area had high temperature and long sunshine duration. High temperature led to large strength reduction, and long sunshine duration accelerated the strength reduction process. Conversely, strength reduction in the northern area was smaller than that in the south. The mapping of CDI and strength reduction aided the understanding of the deterioration zone.

DOI： 10.1007/s00107-015-0952-7

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Phenol-formaldehyde resin-bonded particleboard (PF board), methylene diphenyl diisocyanate resin-bonded particleboard (MDI board), aspen oriented strand board (aspen board), Scots pine oriented strand board (pine board), methylene diphenyl diisocyanate resin-bonded medium-density fiberboard (F-MDI board), and melamine-urea-formaldehyde resin-bonded medium-density fiberboard (F-MUF board)-six board types overall-were subjected to high relative humidity (90 %, 20 A degrees C) or cyclic humidity of high/low relative humidity (90/45 %, 20 A degrees C) for 5 years. The PF board and aspen board showed reduction in bending strength [modulus of rupture (MOR)] and internal bond strength (IB); however, the MDI board, pine board, F-MDI board, and F-MUF board showed almost no reduction. Furthermore, the boards were subjected to outdoor exposure and Test B (boiling for 2 h) from the Japanese Industrial Standard (JIS); the results showed large reduction in the MOR and IB of the PF board and aspen board. In contrast, outdoor exposure did not greatly reduce the MOR and IB of the F-MUF board and F-MDI board. Although the IB of the F-MUF board reduced after the JIS Test B because of using low-durability resin, the IB retention was as high as 87.8 % for 5-year outdoor exposure.

DOI： 10.1007/s10086-015-1494-7

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An outdoor test on particleboards subjected to various climatic conditions was conducted in Japan. The significant climatic factors that reduce the particleboard strength (bending strength and internal bond strength) were investigated using multiple regression analysis. The climatic factors that reduce strength were temperature, sunshine duration, and/or precipitation. These three factors were not always significant; the significant climatic factors were different for each exposure time. In addition, the effects of climatic factors on strength reduction were different. Thus, multiple regression analysis using each climatic factor separately was not powerful. Therefore, the three climatic factors were combined into a first principal component using principal component analysis. The principal component score is referred to as the climate deterioration index (CDI). Strength at each exposure time decreased linearly with increasing CDI. The CDI is simpler and more useful as a climate index than individual climatic factors for predicting the strength reduction. In addition, both the relationship between CDI and strength reduction at each exposure time using analysis of covariance and the effects of CDI and exposure time were significant.

DOI： 10.1007/s00107-015-0918-9

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Particleboard (PB), oriented strand board (OSB), and medium-density fiberboard (MDF) were subjected to various climatic conditions at four sites (Morioka, Tsukuba, Okayama, and Miyakonojo; sites 1, 2, 3, and 4, respectively) in Japan. The reduction in the nail-head pull-through strength and lateral nail resistance strength (both strengths combined are hereafter referred to as nailed board strength) of PB and OSB at sites 3 and 4, which are high-temperature sites, was larger than that at the other sites. Temperature played a significant role in decreasing the nailed board strength. However, the nailed board strength of MDF did not significantly decrease for any site. Biodeterioration, rather than the extraction of wood components and the removal of materials on the board surface, was the main cause of mass loss. In particular, OSB exhibited noticeable biodeterioration. In contrast, there was hardly any biodeterioration in MDF. The correlation between density and nailed board strength was observed to be strong after the outdoor exposure test of PB and OSB.

DOI： 10.1007/s10086-015-1485-8

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The internal bond strength (IB) of a commercial particleboard put under various outdoor exposure conditions were modeled using a multiple linear regression (MLR) and an artificial neural network (ANN). The outdoor exposure data used in this study were collected from the results of past outdoor exposure tests conducted at eight locations across Japan from 2004 to 2011. The data from five locations were used to develop the MLR model and the ANN model for predicting the IB of particleboard under outdoor exposure based on climate data including exposure duration, annual mean temperature, annual sunshine duration, and annual precipitation. The performance of the models was assessed by comparing predicted IB values with measured ones for the remaining three locations. The MLR model gave a high R (2) of 0.87 and a low root mean square error (RMSE) of 0.07 MPa, while the ANN model gave an R (2) of 0.93 and an RMSE of 0.05 MPa. Thus, both models were demonstrated to be applicable to particleboards exposed at different locations in Japan. A statistical test of the MLR model revealed that the IB was influenced negatively by exposure duration, temperature, and precipitation. These influences were confirmed by the sensitivity analysis of the ANN model, and the analysis also showed an additional positive influence of sunshine duration on IB.

DOI： 10.1007/s10086-014-1446-7

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In order to investigate the strength reduction of particleboards subjected to outdoor exposure at eight sites across Japan, the climate factors, i.e., temperature, sunshine duration, and precipitation were analyzed using a principal component analysis. The first principal component (PC1) had an eigenvalue of 2.31 and a proportion of 76.9 %, indicating that the PC1 combines the climate factors into one factor. All of the PC1 eigenvectors demonstrated high, positive values for each climate factor, demonstrating that the first principal component score (PC1 score) increases with increasing temperature, sunshine duration, and precipitation. The PC1 score was introduced as a new index for evaluating strength reduction, as the strength shows a strong correlation with the PC1 score: a higher PC1 score was linked to lower particle-board strength after the outdoor exposure test. The PC1 score can be calculated directly and unambiguously using the climate factors; further, the PC1 score was found to be a more powerful index than each individual climate factors or a combination of them.

DOI： 10.1007/s10086-014-1433-z

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publisher：The Adhesion Society of Japan  

<p>Particleboards were subjected to outdoor exposure at eight sites in Japan, and the reduction in their strength (modulus of rupture and internal bond strength) was analyzed. The strength decreased with increasing thickness change as the particleboards swelled. Furthermore, the strength decreased with increasing mass loss. The correlation coefficients between thickness change and strength and between mass loss and strength were found to be strong. On the other hand, density reduced with increasing thickness change and mass loss. Since density reduction depended on both thickness change and mass loss, the correlation coefficient between density and strength was found to be the strongest. Therefore, it was concluded that density is a simpler and more useful index than thickness change and mass loss. In addition, score of the first principal component calculated by the principal component analysis of the climate factors, namely, temperature, precipitation, and sunshine duration was also found to be a simple and useful index to simplify these factors. A higher score of first principal component resulted in lower strength after the outdoor exposure test.</p>

DOI： 10.11618/adhesion.50.260

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Phenol-formaldehyde resin-bonded particleboard (PF board) and isocyanate resin-bonded particleboard (MDI board) were soaked in water at 40, 70 and 100 A degrees C, and the relationships between soaking conditions and nail joint properties were analyzed. The soaking time to reach the lower limit of nail-head pull-through (NHPT) of the PF board was 2 h at 100 A degrees C, while it took 168 h at 70 A degrees C. The soaking time to reach the lower limit of lateral nail resistance (LNR) of the PF board was 24 h at 100 A degrees C, but it did not take 168 h at 70 A degrees C to reach it. The lower limits of NHPT and LNR for the MDI board were higher than those for the PF board. For the PF board, there was a high correlation between modulus of rupture, internal bond strength and nail joint properties. Based on the results of water soaking and outdoor exposure, it was shown that thickness change has a significant effect on NHPT and LNR, and that the reduction in NHPT and LNR results from the collapse of bonding points owing to swelling of the board.

DOI： 10.1007/s10086-013-1375-x

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Phenol-formaldehyde resin-bonded particleboard (PF board) and isocyanate resin-bonded particleboard (MDI board) were soaked in water at 40, 70 and 100 A degrees C, and the relationships between soaking conditions and board properties were analyzed. The relationships between the deterioration of board properties resulting from water soaking and those arising from outdoor exposure were also analyzed. At 100 A degrees C, the modulus of rupture (MOR) and internal bond strength (IB) of the PF board decreased significantly within the first hour, and subsequently constant values were shown with increasing soaking time. This low constant value was defined as the lower limit. At 70 A degrees C, both the MOR and IB decreased with increasing soaking time, and reached the lower limit. At 40 A degrees C, however, neither decreased significantly with increasing soaking time and neither reached the lower limit. The MOR of the MDI board showed the same trend as the PF board. However, the IB of the MDI board showed a different trend to the PF board, that is, the lower limit of IB required extensive soaking, even at 100 A degrees C. The MOR and IB of both the PF and MDI boards reached the lower limit when thickness change peaked. On the other hand, the MOR and IB for outdoor exposure were lower than those for water soaking, even at the same thickness change. The MOR and IB of water soaking decreased owing to the collapse of the bonding points caused by board swelling. On the other hand, the board properties of outdoor exposure decreased owing to the collapse of the bonding points, and biodegradation also added to the decrease.

DOI： 10.1007/s10086-013-1374-y

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A hot press was used to manufacture particleboards (H boards). A radio-frequency hot press (for RH boards) and an air-injection radio-frequency hot press (for ARH board) were also used, and the effects of air injection on preventing blowout and board properties were analyzed. The thicknesses and densities of manufactured boards were 10 and 30 mm, and 0.6, 0.7, and 0.8 g/cm(3), respectively. The investigation ascertained the effects of air injection in preventing blowout when a radio-frequency hot press is used. The increasing order of temperature was ARH board &gt; RH board &gt; H board during the final pressing stage. For the 30-mm-thick boards, the temperature of H board increased to 100 A degrees C and remained constant at 100 A degrees C even when the pressing time was extended. The temperature of the RH board increased to 100 A degrees C more quickly than in the case of the H board and remained constant at 110-118 A degrees C. The temperature of the ARH board increased linearly to 130-142 A degrees C. For both the 10- and 30-mm-thick boards, the internal bond strength of the RH board was almost the same as that of the ARH board at densities of 0.6 and 0.7 g/cm(3). In contrast, the internal bond strength of the RH board was lower than that of the ARH board at a density of 0.8 g/cm(3). For the 10-mm-thick boards, the thickness swelling in the RH board was almost the same as that in the ARH board irrespective of the density. However, for the 30-mm-thick boards, the thickness swelling in the RH board was higher than that in the ARH board. The low plasticization of particles due to air injection presumably results in a high degree of thickness swelling.

DOI： 10.1007/s10086-013-1351-5

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The effectiveness of air injection for preventing the blowout of particleboards manufactured using a radio-frequency hot press was investigated by evaluating the board properties under artificially created conditions that were conducive to blowout. For evaluation, 10-mm-thick boards with densities of 0.7 and 0.8 g/cm(3) and 20-mm-thick boards with a density of 0.7 g/cm(3) were manufactured. Pressing times for the 10-mm-thick boards were 2, 4, 6, and 8 min, and those for the 20-mm-thick boards were 4, 6, 8, and 10 min. Without air injection, blowout occurred in all manufactured boards. With air injection, however, blowout did not occur in the 10-mm-thick boards with a density of 0.7 g/cm(3). Moreover, air injection prevented blowout even when the board density and board thickness were increased to 0.8 g/cm(3) (for 10-mm-thick boards) and 20 mm (the density was kept at 0.7 g/cm(3)), respectively. Air-injection radio-frequency pressing reduced the pressing time from 4 to 2 min for 10-mm-thick boards, and from 6 to 4 min for 20-mm-thick boards. Moreover, this reduction in the pressing time was achieved without a large reduction in the internal bond strength of the boards.

DOI： 10.1007/s10086-013-1358-y

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DOI： 10.2488/jwrs.59.361

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

Particleboards of different densities (0.6, 0.7 and 0.8 g/cm(3)) and thicknesses (10 and 20 mm) were manufactured from low-moisture particles using an air-injection press. The effects of the air injection on preventing blowout of the boards of different densities and thicknesses were investigated by artificially creating blowout-prone conditions using metal frames. The effects of the air-injection pressure on the board performance were also investigated. 10-mm-thick boards of 0.8 g/cm(3) pressed at 170 A degrees C blew out when air was not injected, but were successfully manufactured by injecting air. 10-mm-thick boards at 150 A degrees C showed constant internal bond (IB), regardless of density, but at 170 A degrees C, IB was higher in boards of higher densities. This was likely due to accelerated hardening of the urea-formaldehyde resin at 170 than 150 A degrees C. At both pressing temperatures, low air-injection pressure did not cause blowout and a reduction in board performance. Air injection also prevented the blowout of thick boards of 20 mm and enabled successful manufacture, showing its effectiveness. The IB of the 20-mm-thick board manufactured using the air-injection press exceeded that of 20-mm-thick board manufactured using an ordinary hot press.

DOI： 10.1007/s10086-013-1323-9

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN WOOD RES SOC  

Particleboards were manufactured from high-moisture raw particles using a radio-frequency press which has both hot-press heating and radio-frequency heating, and the properties of the boards were analyzed. The pressing time was at least 8 mm and the internal bond strength was 0.192 MPa when the boards were manufactured using only hot press heating without radio-frequency heating. However, a reduction in pressing time to just 3 min and an increase in internal bond strength to 0.440 MPa was possible when the board was manufactured using the radio-frequency press. Using the radio-frequency press caused the temperature of the inside of the boards to rise sharply and this resulted in a great reduction in pressing time and an increase in internal bond strength. Moreover, the pressing time was reduced to 2.5 mm and the internal bond strength was increased to 0.552 MPa by installing an air-injection device on the radio-frequency press. Further reduction of pressing time and increase in internal bond strength were achieved by air injection. As a result, it was clarified that the internal bond strength of the boards could be achieved even when the binder resin content was reduced by approximately 25%.

DOI： 10.2488/jwrs.59.90

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Particleboards with thickness of 10 mm and densities of 0.6, 0.7 and 0.8 g/cm(3) were manufactured from high-moisture particles using urea-formaldehyde resin and the effectiveness of air injection was examined. The temperature in the 0.6 and 0.7 g/cm(3) boards was lower with air injection than without during the initial to middle stages of pressing, while the temperature in the 0.8 g/cm(3) board remained lower with air injection than without throughout the entire pressing process. Air injection reduced the pressing time required to manufacture the 0.6 and 0.7 g/cm(3) boards and also increased the internal bond strength of boards of all densities. In the 0.6 and 0.7 g/cm(3) boards, air injection reduced the modulus of rupture (MOR), while in the 0.8 g/cm(3) boards, the MOR was similar between those manufactured by injecting and not injecting air. Air injection was also found to be effective for boards of high densities. The effectiveness of the air injection on thick boards was investigated by manufacturing 20-mm-thick boards of 0.7 g/cm(3). Without air injection, it was not possible to manufacture the 20-mm-thick boards, even by extended hot pressing, but air injection allowed the boards to be manufactured by pressing for 16 min. Air injection was also shown to be effective for manufacturing thick boards.

DOI： 10.1007/s10086-012-1294-2

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Blowouts of particleboards were artificially induced by increasing the vapor pressure inside the boards. Isocyanate resin bonded boards were manufactured from high-moisture particles, and the blowouts and board properties were analyzed. Boards with a high resin content of 5 % showed high bonding strength and did not blow out when pressed at 190 A degrees C, but blew out at a raised temperature of 210 A degrees C to increase vapor pressure inside the boards, thereby showing that blowout occurred when vapor pressure inside the boards exceeded the bonding strength of isocyanate resin. Boards with a low resin content of 2.5 % had low bonding strength and blew out when manufactured without air injection, but were successfully manufactured with air injection that prevents blowouts. However, the injection of high-pressure air reduced the strength properties of the board and increased the coefficient of variation, likely due to the discharge of isocyanate resin from the boards. Therefore, very small local blowouts occurred inside the boards, which lowered the strength properties of some specimens and led to a large coefficient of variation. When the pressure of injected air was lowered, the strength properties increased and the coefficient of variation decreased. This was possibly because the low-pressure air allowed isocyanate resin to remain in the boards, resulting in virtually no parts showing very low-strength properties.

DOI： 10.1007/s10086-012-1298-y

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Various types of wood-based boards were analyzed for deterioration after being exposed to an outdoor environment for 5 years in Tsukuba, Japan. In phenol-formaldehyde resin bonded particleboard (PB(PF)) and aspen oriented strand board (OSB(aspen)), longer exposure caused a greater reduction in the modulus of rupture and internal bond strength, an increase in the coefficients of variation, and a decrease in 95 % lower tolerance limit at the 75 % confidence level (95TL). Nail-head pull-through and lateral nail resistance were also reduced by outdoor exposure, but their coefficients of variation and 95TL were not significantly affected. In contrast, methylene diphenyl diisocyanate bonded medium density fiberboard (MDF(MDI)) only showed a slight deterioration of these properties even after 5-year exposure, and the coefficients of variation and 95TL hardly changed. After 5-year exposure, the retention of shear load in one-plane at relative displacement of 1.0 mm was high in MDF(MDI) and OSB(aspen) at 93.5 and 78.5 %, respectively, but low in PB(PF) at 41.1 %. As with PB(PF), OSB(aspen) also showed a sharp decrease in the modulus of rupture and internal bond strength, but only slightly reduced shear load in one-plane.

DOI： 10.1007/s10086-012-1291-5

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Wood Research Society  

MDI-bonded MDF (MDF(MDI)) and phenol formaldehyde resin bonded particleboard (PB(PF)) were subject to outdoor exposure to investigate their durability. The retention of modulus of rupture, internal bond, nail-head pull-through, and lateral nail resistance of PB(PF) was 46.5, 16.9, 60.9, and 28.0%, respectively, and for MDF(MDI) was 77.1, 96.7, 86.4, and 87.8%, respectively, during a five-year outdoor exposure test at Tsukuba. For the same tests at Miyakonojo, the retention of modulus of rupture, internal bond strength, nail-head pull-through, and lateral nail resistance of PB(PF) was 24.1, 6.73, 52.5, and 22.6%, respectively, and for MDF(MDI) was 75.1, 100, 87.9, and 66.8%, respectively. All retentions of PB(PF) at Miyakonojo, subject to high temperature and precipitation, exceeded those at Tsukuba, but there were no differences between MDF(MDI) at Tsukuba and Miyakonojo. The high durability of MDF was attributable to its smoother surface compared to PB(PF), which prevented rainwater from remaining on the surface and infiltrating into the board due to fiber intertwining.

DOI： 10.2488/jwrs.58.347

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into particleboard and discharges the air through the other plate during press heating. The press can manufacture particleboard from high-moisture particles by controlling blowout of the boards. In this study, the optimum diameter and spacing of the air-injection holes and the effects of pre- and post-pressing were investigated. An optimum hole diameter was not found for the modulus of rupture and thickness swelling for a spacing of either 25 or 50 mm. In terms of internal bond strength, the optimum diameter of the holes arranged at a spacing of 25 mm was 1 mm, but the internal bond strength was not changed by the diameter of holes spaced 50 mm apart. Air injection under all hole conditions reduced the formaldehyde emission from the board. Pre-pressing was tested for further increase in the modulus of rupture and internal bond strength, but was found to have no effect. More efficient use of the air-injection press was achieved by injecting air from the early stages of pressing.

DOI： 10.1007/s10086-012-1269-3

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An air-injection press (AIP) was developed to prevent accidental blowouts of boards during production. In this study, the effects of the AIP on preventing blowouts were investigated by artificially creating a blowout-prone condition, and the press was shown to be effective in preventing blowouts. The modulus of rupture of the boards was almost constant irrespective of pressing time. Longer pressing time resulted in higher internal bond strength when pressed at 170 A degrees C. The thickness swelling of the boards pressed at 170 or 190 A degrees C was almost uniform irrespective of pressing time, and the manufactured boards showed performance similar to those manufactured with an ordinary press. The AIP prevented blowouts sufficiently even when the pressure of the injected air was reduced, and this reduction did not adversely decrease the performance of the boards. Air injection reduced formaldehyde emissions from the board.

DOI： 10.1007/s10086-012-1274-6

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An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into particleboards and discharges the air and vapor through the other plate during press heating. The press can manufacture particleboards from high-moisture particles by preventing blowouts of the boards. In this study, the effects of pressing temperature were investigated by pressing boards at 190, 210, and 230A degrees C. The internal bond strength increased from 0.43 to 0.60 MPa by raising the temperature from 190 to 210A degrees C, but did not increase further when the temperature was raised to 230A degrees C. Raising the temperature from 190 to 210A degrees C also helped improve the thickness swelling. No relationship was found between the modulus of rupture and pressing temperature.

DOI： 10.1007/s10086-011-1246-2

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Adhesion Society of Japan  

DOI： 10.11618/adhesion.48.30

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：FOREST PRODUCTS SOC  

Wood-based boards were exposed to an outdoor environment at angles of 90 degrees and 45 degrees to the ground surface in order to investigate the effect of exposure angle on board properties. In a study on 5-year outdoor exposure, the effects of the exposure angle varied depending on the type of board. Particleboard (PB) and oriented strand board (OSB) deteriorated faster when exposed at 45 degrees compared with 90 degrees, and the difference was more apparent with longer exposure. Five years of exposure at 45 degrees lowered the retention of the modulus of rupture and internal bond of phenolic resin-bonded PB to 15 and 4 percent, respectively. In contrast, medium-density fiberboard (MDF) showed no difference in deterioration between both exposure angles. After 5 years of exposure, the retention of the modulus of rupture was 70 to 80 percent in MDF, while that of internal bond was 81 to 97 percent, thereby showing that the internal bond was better retained than the modulus of rupture. The high durability of MDF was attributable partly to its smoother surface compared with the other boards, which prevented residual rainwater on the surface from infiltrating into the board. Conversely, PB and OSB were prone to surface weathering, which led to the ingress of rainwater. The resultant swelling resulted in the collapse of bonding points, followed by the formation of voids inside the boards. Residual moisture in the voids then caused decay as well as a further reduction in strength (biodegradation).

DOI： 10.13073/0015-7473-62.3.184

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

An air-injection press, which has holes punched in the heating plates, injects high-pressure air through the holes of one plate into boards during press heating. The air-injection press can manufacture boards from high-moisture-content particles by controlling blowouts of the boards. In this study, boards were manufactured from particles that had a moisture content of 25% by using the air-injection press, which reduced the required pressing time. Boards manufactured by injecting air through holes of 5 mm in diameter were of poor quality with a low internal bond strength of only 0.31 MPa. When the hole diameter was reduced to 1 mm, the internal bond strength increased to 0.44 MPa. A high air-injection pressure of 0.55 MPa also resulted in improved board properties over those for boards manufactured at lower pressures. This was probably because a large amount of binder was released from boards through the 5-mm holes, together with water vapor, during air injection; the small-diameter holes reduced the release of binder, resulting in better board properties.

DOI： 10.1007/s10086-011-1210-1

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

An air-injection press was developed to prevent particleboard from blowing out during the manufacturing process. The air-injection press, which has holes punched in the heating plates, injects high-pressure air into the board through the holes of one plate and releases the air through the holes of the other plate. The high-pressure air forces out vapor trapped within the board, thus preventing blowout. The newly developed press reduced the pressing time required for manufacturing board from high-moisture-content particles. However, the manufactured boards exhibited mechanical properties and dimensional stability inferior to conventionally manufactured boards.

DOI： 10.1007/s10086-011-1191-0

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

To improve the properties of particleboard, boards were produced using a sealed press. With the sealed press, boards were processed under high-temperature and high-pressure steam. This increased the saturation temperature, causing a dramatic rise in temperature inside the board, faster curing of the binder, and a shorter pressing time. The boards were bonded with urea formaldehyde resin, melamine urea formaldehyde resin, or poly(methylene diphenyl diisocyanate) (PMDI). The sealed press improved the internal bond strength and thickness swelling of boards regardless of the binder used during the reduced pressing time. The increased bonding strength improved the board properties, allowing PMDI with a lower resin content to be used for bonding the boards.

DOI： 10.1007/s10086-010-1162-x

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER JAPAN KK  

In this study, different properties of experimental particleboard produced using a sealed press were determined and were compared with those for particleboard produced using a conventional press. Three types of binder, namely urea formaldehyde (UF), melamine formaldehyde (MUF), and polymethylene diphenyl diisocyanate (PMDI), were used for board production. For the UF-bonded boards produced using the sealed press, the modulus of rupture and the internal bond strength (IB) decreased due to the high temperature and steam pressure used in comparison to the conditions in a conventional press. However, MUF- and PMDI-bonded boards had improved IB and thickness swelling (TS). For the PMDI-bonded boards, especially, the TS was further improved and IB was increased by using a sealed press. PMDI is known to possess superior properties and was confirmed to achieve good properties when used as a binder for particleboards produced using a sealed press.

DOI： 10.1007/s10086-010-1135-0

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER TOKYO  

Boards were produced by using SP adhesive, which contains styrene-butadiene rubber and polyethylene glycol as major constituents. The use of polyethylene in place of clay, which is also a generally used constituent of SP adhesive, was confirmed to improve board properties. In general, the properties of boards are poorer when produced by two-stage pressing, in which mats are first processed by temporary adhesion and then processed into boards by permanent adhesion; however, the properties of boards produced by two-stage pressing were improved when polyethylene was added to the SP adhesive. In addition, internal bond strength and thickness swelling was greatly improved when boards were produced from ozonized wood and by sealed pressing. Thus, the properties impaired by two-stage pressing were improved by ozonization and sealed pressing.

DOI： 10.1007/s10086-009-1094-5

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2488/jwrs.56.25

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN WOOD RES SOC  

OSB (oriented strand board) was manufactured from wood pallet waste. The pallets were shredded, and small strands were made using a ring flaker. The small strands were 10 mm-mesh screened. as a result long strands in the direction of the fiber were obtained. OSB was manufactured from these strands. In the case of OSB with a target board density of 0.7 g/cm(3), the modulus of rupture was approximately 65 MPa in the oriented direction, and approximately 31 MPa in the perpendicular direction. The modulus of rupture was higher due to orientation. Internal bond strength was approximately 1.0 MPa. Lateral nail resistance and nail-head pull-through were approximately 3.5 kN and 2.5 kN. respectively. These mechanical properties were higher than those of general OSB. Melamine formaldehyde resin was used as a binder. Thickness swelling was approximately 22%, and liner expansion was 0.24%. from 0% to 90% relative humidity. These properties were the same as those of general OSB.

DOI： 10.2488/jwrs.56.412

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JAPAN WOOD RES SOC  

SP adhesive. consisting of styrene-butadiene rubber (SBR) and polyethylene glycol (PEG), has been developed and used to make wood-based boards. This study aimed to improve the wood-based board properties by using ail improved adhesive. ozonization and high mat moisture content. The internal bond strength (IB) was increased 144 times by the improved adhesive. It was also increased by ozonization The optimum ozone charge was 0 5%, which improved the IB 1 35 times When both the improved adhesive and ozonization were used. the IB was doubled and therefore the amount of adhesive could be reduced greatly It is important to decrease the use of adhesive in order to encourage the use of boards because the adhesive is very expensive The cost-saving of this adhesive more than offset the increase in cost of ozonization Although the thickness swelling (TS) of this board was very high, the TS was improved greatly by increasing the mat moisture content.

DOI： 10.2488/jwrs.55.285

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.2488/jwrs.54.183

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Other Link： http://agriknowledge.affrc.go.jp/RN/2010700584

Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG TOKYO  

Fiberboards were prepared from acetylated fibers with various weight gains: 0, 4.7, 9.4, 18.5, and 24.8 weight percent gain (WPG). The effects of low bondability of acetylated fibers on mechanical properties and dimensional changes were determined. The decreased mechanical properties of acetylated fiberboard are mainly due to low bondability. To improve bending strength, high face density, is also needed. The thickness swelling according to JIS and the linear expansion under relative humidity changes decreased with increasing WPG. As for accelerated weathering and the outdoor exposure test, the thickness changes in 4.7-18.5 WPG boards were much higher than those in 0 WPG board and 24.8 WPG board. The high thickness change in 4.7-18.5 WPG boards is due to low bondability. Although 24.8 WPG board also has low bondability, the thickness change of 24.8 WPG board decreased. The high dimensional stability of acetylated fibers, caused by high WPG, probably outweighs the dimensional change caused by low bondability. On the other hand, during the boiling test the thickness changes in 24.8 WPG board and the 4.7-18.5 WPG boards were higher than those in 0 WPG board. The effect of the boiling test on the boards is more severe than that seen with the accelerated weathering and outdoor exposure test; therefore, the effects of the low bondability, probably cancel the effects of the high WPG. It is necessary to increase the bondability of acetylated fibers to improve the dimensional stability and the mechanical properties.

DOI： 10.1007/BF00767894

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Acetylated fibers with a 24.8% weight gain by acetylation were ozonated with 0%-2.0% ozone on fibers. Fiberboards were then made from these treated fibers. The internal bond and bending strength of the acetylated fiberboards increased drastically with increasing ozone charge up to 0.5%-1.0%, whereas the thickness swelling of the fiberboards decreased. Ozone selectively cleaves the aromatic rings of hydrophobic lignin and introduces a hydrophilic carboxyl group into lignin. Thus, the wettability and thermoplasticity of acetylated fibers increased, and this structural modification improved the interfiber contact. Internal bond and bending strength increased as a result. In addition, steep density profiles were formed by the ozonation, resulting in high bending strength. The high compaction ratio accelerated the effect of ozonation. The optimum ozone charges for improving mechanical properties were 0.5%-1.0%.

DOI： 10.1007/BF00776641

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER-VERLAG TOKYO  

The purpose of this study was to reveal the effects of various levels of mat-moisture content (m.m.c.) and the closed-press system for making single- or three-layer particleboard on the density profile, thickness swelling, specific moduli of elasticity (MOE) and rupture (MOR) and internal bond strength. Internal gas pressure was measured in an enclosed frame; and the larger the m.m.c., the higher the internal gas pressure became. When rising water vapor (steam) struck particles, it plasticized them and cured the adhesive, resulting in improved interparticle contact. The vertical density gradient in the three-layer board was larger than that in the single-layer board. As for thickness swelling by cold-water soaking, the single-layer boards were less affected than the three-layer boards and showed good dimensional stability with increased m.m.c. The open-system boards swelled more than the closed-system boards. The closed-system single-layer board made at high m.m.c. returned nearly to the prime thickness by air-drying after coldwater soaking. Specific MOE and MOR were larger at 15% or 10% m.m.c. than those at other m.m.c. Considerable reductions of specific MOR and MOE of the closed-system three-layer board were observed at 20% or 25% m.m.c.

DOI： 10.1007/BF01177913

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Language：Japanese   Publishing type：Research paper (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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J-GLOBAL

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Language：Japanese  

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Language：Japanese  

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Other Link： http://agriknowledge.affrc.go.jp/RN/2010541385

Language：Japanese   Presentation type：Oral presentation (general)  

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Application no：特願2010-034348  Date applied：2010.2.19

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Application no：特願2008-272655  Date applied：2008.10.23

Announcement no：特開2010-99904  Date announced：2010

Date published：201056

Patent/Registration no：特許第5663726号  Date issued：2011.12.19

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Application no：特願2008-024820  Date applied：2008.2.5

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Application no：特願DE199 57 329 B4  Date applied：2005.12.22

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Announcement no：特開2004-17475  Date announced：2004.1.22

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Application no：特願平10-343468  Date applied：1998.12.2

Announcement no：特開2000-167813  Date announced：2000.6.20

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Application no：特願United States Patent 5,814,170  Date applied：1998.9.29

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Application no：特願United States Patent 5,786,063  Date applied：1998.7.28

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Application no：特願平8-238673  Date applied：1996.8.22

Announcement no：特開平10-58411  Date announced：1998.3.3

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Application no：特願平5-281062  Date applied：1993.11.10

Date announced：1995.5.23

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