CN115139380A - Wood strengthening treatment method and carbon material thereof - Google Patents
Wood strengthening treatment method and carbon material thereof Download PDFInfo
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- CN115139380A CN115139380A CN202210767327.6A CN202210767327A CN115139380A CN 115139380 A CN115139380 A CN 115139380A CN 202210767327 A CN202210767327 A CN 202210767327A CN 115139380 A CN115139380 A CN 115139380A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
- B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
- B27K5/001—Heating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27D—WORKING VENEER OR PLYWOOD
- B27D3/00—Veneer presses; Press plates; Plywood presses
- B27D3/02—Veneer presses; Press plates; Plywood presses with a plurality of press plates, i.e. multi- platen hot presses
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E50/00—Technologies for the production of fuel of non-fossil origin
- Y02E50/10—Biofuels, e.g. bio-diesel
Abstract
The embodiment of the application discloses a wood strengthening treatment method and a carbon material thereof, wherein a treatment material is compressed under the conditions of set treatment temperature and treatment pressure, the treatment material is in an absolutely dry state, and the treatment temperature is greater than or equal to the softening temperature of wood. The wood strengthening treatment method is carried out on the wood in an absolutely dry state, plastic deformation is permanently fixed when compression is completed, moisture migration is not required to be considered, pressure maintaining is not required to release internal pressure generated by moisture, and further shrinkage of the treated wood reaching the set compression ratio can occur after pressure relief cooling, so that the treatment period can be greatly shortened, the treatment energy consumption and the production cost are reduced, the design and the execution of the compression process are relatively simple, instantaneous rebound, bulging and cracking of pressure relief caused by unmatched pressure maintaining time can not occur.
Description
Technical Field
The invention relates to the technical field of wood material strengthening treatment, in particular to a wood strengthening treatment method and a carbon material prepared by the treatment method.
Background
At present, compression and densification treatment is a main strengthening treatment means of low-density wood materials, and can improve the properties of the low-density wood materials such as density, mechanical strength and the like. The principle of compression and densification treatment is that under the conditions of certain water content and high temperature, the bonding force among molecules is weakened, and the thermal movement of the molecules is accelerated, so that the wood is converted from an elastic state to a plastic state, and is compressed under the pressure condition to generate plastic deformation. Further, the plastic deformation is fixed by physical or chemical means.
For example, in a Chinese patent database, the invention patent with the publication number of CN101214675B and the name of "wood hot-pressing carbonization strengthening method" discloses a wood compression densification treatment method and a deformation fixing method thereof, which comprises the steps of implementing 5-50% compression densification treatment on wood under the pressure conditions of 3-17% of water content and 200-260 ℃, and then carrying out hot-pressing carbonization treatment for 120-240 min to prepare a wood section bar which is subjected to compression densification treatment and fixed deformation. Also, for example, patent of invention with publication number CN103481348B entitled "an integrally strengthened solid wood section and method for manufacturing the same" discloses preheating wood for 180 to 600 seconds under the pressure condition of water content of 1 to 3% and temperature of 160 to 210 ℃, performing 20 to 30% compression and densification treatment, and after maintaining the pressure for 180 to 600 seconds, performing heat treatment for 2 to 4 hours in normal pressure hot medium with dry bulb temperature of 180 to 200 ℃ to fix plastic deformation. Although the means for fixing plastic deformation are different, the two technical means adopt the treatment process of firstly carrying out compression densification treatment and then fixing plastic deformation.
Meanwhile, in the prior art, a technical means for obtaining a wood profile subjected to compression densification treatment on a layer with a specific thickness by controlling the migration of moisture in the wood is provided.
For example, the invention patent with publication number CN102554992B entitled "a surface enhanced wood section and method for manufacturing the same" discloses a surface compression densified section with a compression ratio of 5-20% obtained by hot pressing wood at a temperature of 230-320 ℃ and a moisture content of 4-15% for 30-600 s. In this solution, since only the surface of the wood is compressed and densified, the way of fixing plastic deformation of this solution is achieved by slow pressure relief and cooling under cold or negative pressure conditions. Also disclosed is a method for producing a dense solid wood board with controllable density distribution, which comprises forming a dry region and a wet region in the thickness direction of the wood, controlling the yield stress difference between the dry region and the wet region to be above 0.2MPa, plastically deforming the wet region by hot pressing at 100-150 ℃, maintaining the pressure for 5min, releasing the pressure, maintaining the pressure for 30min, and finally performing heat treatment in a normal pressure or pressure hot medium at 180 ℃ for more than 1h to fix the plastic deformation. Also, as disclosed in publication No. 114147827A entitled "method for compressing laminated solid wood based on moisture distribution control", the present invention discloses a method for compressing laminated compressed wood with specific thickness by immersing wood with moisture content of 6-28% in water for 1-20 h to form a moisture content distribution state with high surface moisture content and low internal moisture content, driving the internal moisture migration of the wood at 40-240 ℃, and performing compression and densification treatment under the conditions of the same temperature and compression speed of 0.1-2 mm/s to obtain the laminated compressed wood profile with specific thickness. The three technical schemes are used for realizing compression and densification treatment on the specific thickness layer of the wood section by controlling the moisture migration position in the wood.
Disclosure of Invention
However, through the creative research and discovery of the inventor, the above means for implementing the integral compression densification treatment on the wood material has the following defects:
1. in the process of compression and densification, pressure maintaining treatment with a relatively long duration is needed to temporarily fix deformation formed by compression; however, the dwell time is greatly affected by the tree species, the initial moisture content, the hot pressing temperature, and other factors, so it is not easy to determine an accurate and appropriate dwell time.
2. The prior art has recognized that the conditions under which compression deformation occurs are that compression deformation must occur under damp heat conditions, and therefore the factors that need to be controlled in the compression process include the temperature, the water content, and the applied external force within the wood, and only when the applied external force is greater than the yield stress of the specific layer, the yield stress of the specific layer is affected by the interaction of the temperature and the water content within the wood, and thus the control process is complicated.
3. When the pressure maintaining time is insufficient, the compression deformation of the wood material can cause the problems of rebound, wood compression bulge and even burst at the instant of pressure relief.
4. The two factors of the water content and the hot pressing temperature have an interactive relation in the compression and densification treatment, and under the condition that one or both of the two factors are too high, the wood material is easy to have the defects of internal cracking, explosion and the like in the compression and densification treatment process.
5. The plastic deformation formed by compression densification treatment needs to be fixed by physical or chemical means, and the fixed plastic deformation treatment process has the disadvantages of large energy consumption, long period and relatively high cost; more importantly, the fixing effect is at the expense of the loss of material properties, such as mass loss and mechanical properties, regardless of the fixing means (hot pressing, heat treatment, saturated steam treatment, superheated steam pressure treatment, etc.). See "the research progress of the damp-heat fixing technology and mechanism of plastic deformation of wood" (Huangrongfeng, the authors, vol.58, 2 nd, 2022 nd month).
The above means for implementing the compression densification treatment of the wood material with a specific thickness layer has the following defects:
even if a layer having a certain thickness (for example, a thickness of 5mm below the surface) of the treatment material is compressed, the layer having the certain thickness needs to be compressed only after the entire softening of the layer having the certain thickness is completed. The reason why this has to be done is that the moisture present in the wood forms a thermal resistance, the temperature of the wood itself is difficult to rise, and the moisture migrates during heating, and only the entire thickness layer to be compressed is softened and then compressed in order to control the softened layer and sufficiently soften it.
Therefore, in the prior art, the water content of the layer with the specific thickness is distinguished from the water content of the layers with other thicknesses (higher than the water content of the layers with other thicknesses), so that the yield stress of the water content of the layer with the specific thickness under the condition of the treatment temperature is smaller than that of the layers with other thicknesses and the applied external force. However, the formation of a layer of a specific thickness (wet area) and the control of the migration position thereof are quite complicated processes. Firstly, calculating according to the required density peak value distribution position in the thickness direction of the wood through two groups of formulas to obtain the maximum moisture content distribution position and the heating time in the thickness direction of the wood, and then calculating through a group of formulas to obtain a wood soaking scheme. The calculation process is complex and difficult to control, and is greatly influenced by factors such as wood tree species, wood grain direction, initial moisture content and the like, so that the error is relatively large.
In view of the above-mentioned means for carrying out the overall compression densification treatment on the wood material and the above-mentioned means for carrying out the layer compression densification treatment on the wood material with a specific thickness, the inventors have found that the product or process defects thereof result from the prior art understanding of the prerequisites for the compression densification treatment. The prior art considers that the moisture absorption expansibility and thermoplasticity of the wood cell wall components and the porous structure of the wood form the premise of plastic deformation of the wood, and the wood compression can be realized by applying an external force which is more than or equal to the yield stress of the wood (influenced by the moisture content and the softening temperature of the wood) from the direction vertical to the fibers under the wet and hot conditions; the energy stored in the wood in the dry set state is released in the damp and hot environment, which causes the plastic deformation to recover (commonly called compression rebound), so the damp and hot fixing means is needed to fix the plastic deformation in a way of releasing the internal stress of the wood after the compression densification treatment.
Based on the findings, the inventor overcomes the prejudice of the prior art, and further finds that the existence of moisture in the wood is the main reason of the problems of complex control process, large control difficulty, relatively low success rate and the like of the compression densification treatment in the prior art, but is not the necessary condition for softening and plastic deformation of the wood.
In particular, the prior art recognizes that high temperatures are necessary to soften wood under aqueous conditions, softening being the result of the transition of the wood from an elastic state to a plastic state, so that the wood can be compressed or bent. However, the transition from the elastic state to the plastic state is reversible, so that if there is no fixing treatment for plastic deformation, the wood will return to the state before compression to some extent or completely after the conditions for compression densification are removed.
The technical problem to be solved by the present invention is to provide a method for strengthening wood, which can effectively solve at least one of the above problems; the invention also provides the carbon material prepared by the treatment method.
One embodiment of the invention provides a wood strengthening treatment method, wherein a treatment material is compressed under the conditions of set treatment temperature and treatment pressure, the treatment material is in an oven dry state, and the treatment temperature is greater than or equal to a wood softening temperature.
Preferably, the treatment temperature is 240 ℃ or higher.
Preferably, the treatment temperature is 240 ℃ to 280 ℃.
Preferably, the water content of the treated material is 0 ± 1.0%.
Preferably, the treatment temperature is conducted from the side to which heat is applied to the other side in the compression direction of the treatment material; at the same time, the processing temperature is advanced to the sub-thickness layer with the compression feed.
Preferably, the treatment temperature is advanced with the advancement of the compression, while the advancement, with the conduction of the treatment temperature, enables the compression to continue to advance.
Preferably, the time taken from the first unit thickness layer to reach the treatment temperature to the last unit thickness layer completing the compression is less than 5 minutes.
Preferably, after the processed material reaches a set compression rate, directly decompressing and discharging; or after pressure relief, the material is kept discharged again after the thickness of 10s to 30 s.
Preferably, the set compression ratio is smaller than the actual compression ratio.
Preferably, the set compression ratio is smaller than the actual compression ratio by 0 to 10%.
Another embodiment of the present invention provides a carbonaceous material produced by the above-described wood strengthening treatment method, wherein the equilibrium water content of the carbonaceous material is 7% to 9% at 20 ℃/95% RH.
Preferably, the carbonaceous material shrinks 0 to 10% in volume from the production to the cooling.
Preferably, the tree species for making the carbon material is redwood, rice-wood raft, rubber wood, lychee wood, cedar wood, pine wood, poplar wood, paulownia, sapanwood, eucalyptus wood or topaz wood.
In summary, compared with the prior art, the invention has the beneficial effects that:
1. the treatment temperature reaches the softening temperature of the wood, the wood can be compressed under the anhydrous condition, the plastic deformation is not required to be fixed by an additional curing means, and the plastic deformation is already permanently fixed when the compression is finished, so the technical scheme of the invention can greatly shorten the treatment period and reduce the treatment energy consumption and the production cost.
2. The compression is carried out under the condition of no water in the wood, the migration of water is not needed to be considered, and the pressure is not needed to be maintained to release the internal pressure generated by the water, so the design and the execution of the compression process are relatively simple; the situations of instant rebound, bulge and explosion caused by non-adaptive pressure maintaining time can be avoided.
3. The treatment temperature reaches the softening temperature of the wood and simultaneously the softening of the wood is completed so as to be able to be compressed, and the progress of the treatment temperature and the advance of the compression can be performed in cooperation, so that the efficiency of the compression treatment can be further improved.
4. The processing material (or the partial thickness layer of the processing material) is still in a plastic body state at the moment of pressure relief, the volume of the processing material (or the partial thickness layer of the processing material) reaching the set compression ratio can be further contracted after pressure relief and cooling, and the set compression ratio is smaller than the actual compression ratio during the compression process, so that the energy consumption in the compression processing process can be reduced, and the production cost is reduced.
5. The invention only needs to control the compression temperature, and when the temperature of the material of the thickness layer to be compressed is higher than the softening temperature of the wood, the compression deformation can be generated, so the control of the compression process is very simple.
Detailed Description
In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The embodiment of the application discloses a wood strengthening treatment method, which is a strengthening treatment means for compressing a treatment material (such as redwood, millennia wood, rubber wood, lychee wood, fir wood, pine wood, poplar wood, paulownia, sapanwood, eucalyptus wood or yellow beam wood) under the conditions of set treatment temperature and treatment pressure to generate plastic deformation so as to obtain a densification effect. In particular, when the strengthening treatment is performed, the treated material is in an absolutely dry state, and the treatment temperature is not lower than the softening temperature of the wood.
By means of the method, the inventor creatively discovers that the moisture is not one of the necessary conditions for softening and plastic deformation of the wood. Under the anhydrous condition (namely an oven dry state), the wood can be softened only by heating the treatment material to the softening temperature of the wood, and then the softened wood can be subjected to plastic deformation by applying pressure, so that the strengthening treatment of the treatment material is realized in a compression and densification mode. In contrast to the prior art, in this example, the effect of high temperature on wood is to transform the wood from an elastomer to a plastomer, and the transformation process is irreversible. Since the wood is converted into a plastic body, the plastic deformation caused by compression is not reversible, so that the plastic deformation does not need to be fixed by an additional curing means, but the plastic deformation is permanently fixed when the compression is finished, and therefore, the technical scheme of the embodiment can greatly shorten the treatment period and reduce the treatment energy consumption and the production cost. Meanwhile, the compression is carried out under the condition of no water in the wood, the migration of water is not needed to be considered, and the pressure is not needed to be maintained to release the internal pressure generated by the water, so the design and the execution of the compression process are relatively simple; the situations of instant rebound, bulge and burst of pressure relief caused by unmatched pressure maintaining time can be avoided.
Specifically, the wood strengthening treatment method comprises a drying step and a compression and densification step.
The drying step is to dry the treated material to a constant weight at 103 ℃ to 130 ℃ so that the treated material is in an oven-dried state, for example, 0 ± 1.0%.
There are two embodiments of the step of compressing and densifying.
In the first embodiment, after the thickness layer to be compressed (which may be a part of the thickness of the material or the entire thickness) of the material reaches the processing temperature, the material is pressed to complete the compression. Specifically, the heating component heats the processing material in an absolute dry state in a non-pressure state, the processing temperature is conducted from one side to the other side in the compression direction of the processing material until the whole thickness layer to be compressed reaches the processing temperature to be softened, and then the pressure component presses the softened thickness layer to be compressed in the absolute dry state to enable the whole thickness layer to be compressed to be subjected to plastic deformation. If the thickness layer to be compressed is part of the thickness of the treated material, a carbon-wood composite profile is produced, wherein the compression-strengthened thickness layer forms the carbon material layer in the composite profile, and the remaining thickness layer which is not compression-strengthened forms the wood material layer in the composite profile. If the thickness layer to be compressed is the whole thickness of the treated material, the carbon material, i.e. the carbon section, is obtained. The time taken from the start of heating by the heating means to the completion of the compression should be less than 5 minutes, in other words, the process of the compression treatment should be completed within 5 minutes.
The second embodiment is that the conduction, the progression and the feeding of the compression of the treatment temperature on the thickness layer to be compressed of the treatment material are carried out in coordination. Specifically, the pressure member presses the treatment material and compresses a part of the thickness layer to be compressed that has reached the treatment temperature while the heating member is in contact with the surface of the treatment material or after the hot-pressing member is in contact with the surface of the treatment material and before the entire thickness layer to be compressed reaches the treatment temperature. After the compression of the softened caliper layer is completed, the heating member transfers heat to the sub-caliper layer below the completed compressed caliper layer and softens it, while the pressure member can continue to feed to compress the softened sub-caliper layer. In this process, the conduction of the treatment temperature is continuous, the treatment temperature is simultaneously progressive with the advance of the compression, and the conduction and progression of the treatment temperature enable the continuous advance of the compression. The heat of the heating component can be transferred to the secondary thickness layer in a progressive mode besides the heat conduction mode, so that the temperature rising speed of the inner layer of the processing material can be increased, and the compression efficiency is increased. Of course, the time taken from the start of heating by the heating means to the completion of compression should be less than 5 minutes.
The set compression ratio of the processing material is a compression ratio that can be achieved by the setting of the pressure member, and the actual compression ratio is a compression ratio that the processing material actually needs to achieve. In the technical scheme of the application, the set compression ratio is smaller than the actual compression ratio.
As is well known to those skilled in the art, the porous structure of wood enables the wet expansion and dry shrinkage rule to dominate the size and shape change of wood, while the expansion and contraction rule only has little or no influence on the size and shape of wood. However, in the present application, the treated material in an absolutely dry state is heated to a softening temperature of the wood, and then undergoes a transition from an elastomer to a plastomer, and the dimension of the wood in the plastomer state is mainly affected by the rule of expansion and contraction of heat, and is only to a very small extent or hardly affected by the rule of expansion and contraction of moisture. The processing material is still in a plastic body state at the moment of pressure relief, so that the processing material can shrink in the pressure relief and cooling process. Therefore, the set compression ratio of the technical scheme of the application is smaller than the actual compression ratio, so that the energy consumption in the compression treatment process can be reduced to a certain extent, and the production cost is reduced.
The method comprises the steps of treating a treated material to be compressed and densified when the treated material reaches a set compression ratio, directly decompressing and discharging the treated material after the treated material reaches the set compression ratio, or decompressing and discharging the treated material after the treated material is maintained for 10-30 s after decompression to obtain the carbon material (if a layer with the thickness to be compressed is part of the thickness of the treated material, a carbon-wood composite section is prepared, and if the layer with the thickness to be compressed is the whole thickness of the treated material, the prepared carbon material is the carbon section). Finally, controlling the water content of the carbon material under the conditions of 50-60 ℃ and 85-90% of relative humidity, and controlling the water content of the carbon material in the carbon section or the carbon wood composite section to 6-8%. The equilibrium water content of the carbon material in the prepared carbon section or carbon wood composite section is 7-9% in the environment of 20 ℃/95% RH.
The technical solution of the present application is further illustrated by the following specific examples. In the embodiment of the application, the drying treatment adopts a blast type drying box, the heating part and the pressure part for the compression treatment are flat plate type hot presses, and the moisture content of the prepared carbon-wood composite section or carbon section is controlled to be implemented in a balance drying kiln.
Example 1
The treated wood is a poplar wood plate with the thickness of 20mm, firstly, the treated wood is dried to balance weight under the condition of 103 +/-2 ℃, and the water content of the dried treated wood is 0.5 to 1.0 percent.
Subsequently, the temperature of the upper and lower press plates was raised to 250 ℃, and the stop position for pressing down the upper press plate was defined using a thickness gauge having a thickness of 19mm (i.e., a set compressibility of 5%), with the upper and lower press plates being controlled to have a gap of 22mm.
Then, the treatment material was placed between the upper and lower press plates, and the upper press plate was rapidly lowered to the surface where the upper press plate contacted the treatment material, and pressure was applied after the upper press plate contacted the surface of the treatment material for 90 seconds (preheating). In this embodiment, during the 90s preheating process, the processing temperature is transferred to the thickness layer of about 0.9mm inward from the upper and lower surfaces of the processing material (i.e. the thickness layer to be compressed in this embodiment, the thickness is referred to the thickness of the original processing material). After the pressing, the thick layer was compressed to form 2 carbon material layers (surface dense layers) each having a thickness of about 0.4mm on the upper and lower surfaces of the treated material, and an uncompressed wood layer was formed between the two carbon material layers. In the compression process, the pressure of the pressing plate is 6MPa, the pressing speed of the upper pressing plate is 4mm/min, namely 15s can finish the compression process and reach the set compression ratio, and the total processing time of the pressing plate and the pressing speed plus the preheating time is 105s.
And then, the flat plate type hot press is decompressed, but the interval between the upper pressing plate and the lower pressing plate is kept at 19mm, the press is opened to discharge after the thickness is kept for 10s, and the carbon-wood composite section with the total thickness of 18.98mm and the thickness of the carbon material layer of 0.38mm is prepared.
Finally, the water content of the carbon material part of the carbon-wood composite section is controlled to be 6-8% under the conditions of 50 ℃ and 85% of relative humidity.
Example 2
The processing method of example 2 is substantially the same as that of example 1, except for differences in processing temperature, set compression ratio, time taken for compression, and the like. Specifically, the thickness gauge is 18mm thick, so the set compression rate of the present embodiment is 10%; the temperature of the upper and lower platens was 260 deg.C, so the treatment temperature in this example was 260 deg.C and the platen pressure was 5.5MPa. The upper platen is pressed while contacting the treatment material. In the compression process, assuming that a thickness layer of 0.01mm is used as a unit thickness layer, when the pressing plate contacts the upper surface and the lower surface of the processing material to enable the first unit thickness layer to reach the processing temperature and soften, the upper pressing plate can perform downward pressing feeding to compress the first unit thickness layer, the upper pressing plate and the lower pressing plate can be closer to a secondary thickness layer in the compressed thickness layer along with the downward pressing feeding (compression feeding) of the upper pressing plate, the processing temperature also gradually increases to the secondary thickness layer to soften the secondary thickness layer, and the upper pressing plate can continue to perform downward pressing feeding to compress the secondary thickness layer. And finally, finishing the compression treatment after the set compression rate is reached along with the layer-by-layer progressive treatment of the temperature and the pressure. The pressing speed of the upper pressing plate is 2mm/min, so that 60s can finish the compression process and reach the set compression rate. The temperature and heat are transferred to the thickness layer of about 1.6mm from the upper and lower surfaces of the processed material (i.e. the thickness layer to be compressed in this embodiment, the thickness is referred to the thickness of the original processed material) within 60s, so as to form 2 carbon material layers (surface compact layers) with a thickness of about 0.6mm, which are respectively located on the upper and lower surfaces of the processed material, and a wooden layer without being compressed and strengthened is located between the two carbon material layers.
In the embodiment, the press is opened to discharge after the thickness is kept for 20s, and the carbon-wood composite section with the total thickness of 17.96mm and the carbon layer thickness of 0.58mm is obtained.
Example 3
In example 3, the same treatment temperature as in example 1 and the same drying method of the treatment material were used, but the treatment temperature was 240 ℃ and the thickness gauge thickness was 17mm, so that the set compression amount was 15%.
And (3) placing the processing material between the upper pressing plate and the lower pressing plate, quickly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, keeping (preheating) the upper pressing plate after contacting the surface of the processing material for 15s, and continuously pressing the upper pressing plate downwards and applying pressure to the processing material. In the present embodiment, in the compression direction, the processing temperature is first transferred (heat conduction) from the upper and lower surfaces of the processing material toward the core layer side as the contact time of the platen with the processing material continues, and then transferred (heat conduction and heat transfer occur simultaneously) from the upper and lower surfaces of the processing material toward the sub-thickness layer on the core layer side as the contact time of the platen with the processing material continues and the press-down feed of the upper platen continues. In the compression process, the pressure of the pressing plate is 6MPa, the pressing speed of the upper pressing plate is 1mm/min, namely 180s can finish the compression process and reach the set compression ratio. The processing temperature can be transferred and increased to the layer with the thickness of about 2.4mm inwards from the upper surface and the lower surface of the processing material in the preheating process of 15s and the compression process of 180s, so that 2 carbon material layers with the thickness of about 0.9mm are formed and are respectively positioned on the upper surface and the lower surface of the processing material, and an uncompressed wood layer is arranged between the two carbon material layers.
In the embodiment, the press is opened to discharge after the thickness is kept for 30s, and the carbon-wood composite section with the total thickness of 17mm and the carbon material layer thickness of 0.9mm is obtained.
Example 4
The treated material of this example was pine wood with a thickness of 20mm, and the drying conditions were 110. + -. 2 ℃ and the water content of the treated material after weighing was 0.2% to 0.5%. The processing temperature was 250 ℃ and the thickness gauge thickness was 17mm, so the set compression was 15%.
The processing material is placed between the upper pressing plate and the lower pressing plate, the upper pressing plate is rapidly lowered to the surface of the upper pressing plate contacting the processing material, the upper pressing plate is kept (preheated) for 30s after contacting the surface of the processing material, and the upper pressing plate continues to press downwards and applies pressure to the processing material. In the compression process, the pressure of the pressing plate is 6MPa, the pressing speed of the upper pressing plate is 1mm/min, namely 180s can finish the compression process and reach the set compression ratio. The processing temperature can be transferred and increased to the layer with the thickness of about 2.7mm inwards from the upper surface and the lower surface of the processing material in the preheating process of 30s and the compression process of 180s, so that 2 carbon layers with the thickness of about 1.2mm are formed and are respectively positioned on the upper surface and the lower surface of the processing material, and an uncompressed wood layer is arranged between the two carbon material layers.
In the embodiment, the carbon-wood composite section with the thickness of 16.94mm and the thickness of the carbon material layer of 1.17mm is prepared by directly discharging after pressure relief.
Example 5
The treated material of this example was eucalyptus wood with a thickness of 16mm, and the drying conditions were 110. + -. 2 ℃ and the water content of the treated material after weighing was 0.2% to 0.5%. The processing temperature was 280 ℃ and the thickness of the gauge was 13mm, so that the set compression amount was 18.7%.
The processing material is placed between the upper and lower pressing plates, the upper pressing plate is rapidly lowered to the surface where the upper pressing plate contacts the processing material, and pressure is applied while the upper pressing plate contacts the surface of the processing material. In the compression process, the pressure of the pressing plate is 5MPa, and the pressing speed of the upper pressing plate is 2.5mm/min, namely 72s can finish the compression process and reach the set compression ratio. The processing temperature can be transferred and increased to the layer with the thickness of about 2.5mm inwards from the upper surface and the lower surface of the processing material in the compression process of 72s, so that 2 carbon material layers with the thickness of about 1.0mm and respectively positioned on the upper surface and the lower surface of the processing material are formed, and a wood layer which is not subjected to compression strengthening is arranged between the two carbon material layers.
In the embodiment, the press is opened to discharge after the thickness is kept for 15s, and the carbon-wood composite section with the thickness of 12.86mm and the thickness of the carbon material layer of 0.93mm is prepared.
Example 6
The treated wood of the embodiment is Milao wood with a thickness of 14mm, the drying condition is 110 +/-2 ℃, and the water content of the treated wood after weighing is 0.2-0.5%. The processing temperature was 250 ℃ and the thickness gauge thickness was 10mm, so the set compression was 28.6%.
And placing the processing material between the upper pressing plate and the lower pressing plate, quickly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, and continuously pressing the upper pressing plate downwards and applying pressure to the processing material while the upper pressing plate contacts the surface of the processing material. In the compression process, the pressure of the pressing plate is 6MPa, the pressing speed of the upper pressing plate is 2mm/min, namely the compression process can be completed within 120s, and the set compression ratio is reached. The processing temperature can be transferred to the layer with the thickness of about 4.3mm inwards from the upper surface and the lower surface of the processing material in the 120s compression process, so that 2 carbon material layers with the thickness of about 2.3mm are formed and are respectively positioned on the upper surface and the lower surface of the processing material, and an uncompressed wood layer is arranged between the two carbon material layers.
In the embodiment, the press is opened to discharge after the thickness is kept for 15s, and the carbon-wood composite section with the thickness of 9.96mm and the carbon material layer thickness of 2.28mm is prepared.
Example 7
The treated material of this example was fir wood with a thickness of 12mm, and the drying conditions were 120. + -. 2 ℃ and the water content of the treated material after weighing was-0.2% to 0.2%. The processing temperature was 260 ℃ and the thickness of the gauge was 8mm, so that the set compression amount was 33.3%.
And placing the processing material between the upper pressing plate and the lower pressing plate, quickly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, and continuously pressing the upper pressing plate downwards and applying pressure to the processing material while the upper pressing plate contacts the surface of the processing material. In the compression process, the pressure of the pressing plate is 5MPa, the pressing speed of the upper pressing plate is 2mm/min, namely the compression process can be completed within 120s, and the set compression ratio is reached. The treatment temperature can be transferred to the whole thickness layer of the treatment material in the process of 120s of compression and heat progression, and the treatment effect of overall densification is formed.
In this example, the press was opened to discharge after the thickness was maintained for 15 seconds, and a carbon profile having a thickness of 7.9mm was produced.
Example 8
The treated material of this example was fast-growing rubber wood 10mm thick, and the drying conditions were 120. + -. 2 ℃ and the water content of the treated material after weighing was-0.2% to 0.2%. The treatment temperature was 260 ℃ and the thickness gauge thickness was 6mm, the set compression amount is 40%.
And placing the processing material between the upper pressing plate and the lower pressing plate, quickly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, and continuously pressing the upper pressing plate downwards and applying pressure to the processing material while the upper pressing plate contacts the surface of the processing material. In the compression process, the pressure of the pressing plate is 5MPa, the pressing speed of the upper pressing plate is 2mm/min, namely the compression process can be completed within 120s, and the set compression ratio is reached. The treatment temperature can be transferred to the whole thickness layer of the treated material in the process of 120s of compression, heat conduction and heat progression, and the treatment effect of integral densification is formed.
In the embodiment, the press is opened to discharge after the thickness is kept for 15s, and the carbon section with the thickness of 5.7mm is prepared.
Example 9
The treated material of this example was redwood with a thickness of 10mm, the drying conditions were 130. + -. 2 ℃ and the water content of the treated material after weighing was-1% to 0.5%. The processing temperature was 280 ℃ and the thickness gauge thickness was 6mm, so the set compression was 40%.
The processing material is placed between the upper pressing plate and the lower pressing plate, the upper pressing plate is rapidly lowered to the surface of the upper pressing plate contacting the processing material, the upper pressing plate is kept (preheated) for 30s after contacting the surface of the processing material, and the upper pressing plate continues to press downwards and applies pressure to the processing material. In the compression process, the pressure of the pressing plate is 7MPa, the pressing speed of the upper pressing plate is 3mm/min, namely the compression process can be completed within 80s, and the set compression ratio can be reached. The treatment temperature can be transferred to the whole thickness layer of the treatment material in the processes of 30s preheating, 80s compression, heat conduction and heat progression, and the treatment effect of integral densification is formed.
In the embodiment, the carbon section with the thickness of 5.6mm is prepared by directly discharging after pressure relief.
Example 10
The treated material of this example was cedar with a thickness of 8mm, and the drying conditions were 130. + -. 2 ℃ and the water content of the treated material after weighing was-1% to 0.5%. The processing temperature was 260 ℃ and the thickness of the gauge was 4.5mm, so that the set compression amount was 43.7%.
And (3) placing the processing material between the upper pressing plate and the lower pressing plate, rapidly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, keeping (preheating) the upper pressing plate for 60s after contacting the surface of the processing material, and continuously pressing the upper pressing plate and applying pressure to the processing material. In the compression process, the pressure of the pressing plate is 7MPa, the pressing speed of the upper pressing plate is 2mm/min, namely, the compression process can be completed within 106s, and the set compression ratio is reached. The treatment temperature can be transferred to the whole thickness layer of the treatment material in the processes of preheating for 60s and compressing, heat conduction and heat progression for 106s, and the treatment effect of integral densification is formed.
In the embodiment, the carbon section with the thickness of 4.3mm is prepared by directly discharging after pressure relief.
Example 11
The treated wood of this example is poplar with a thickness of 6mm, the drying conditions are 130 + -2 deg.C, and the water content of the treated wood after weighing is-1% to 0.5%. The processing temperature was 270 ℃ and the thickness gauge thickness was 3.5mm, so the set compression amount was 41.7%.
And (3) placing the processing material between the upper pressing plate and the lower pressing plate, quickly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, keeping (preheating) the upper pressing plate after contacting the surface of the processing material for 60s, and continuously pressing the upper pressing plate downwards and applying pressure to the processing material. In the compression process, the pressure of the pressing plate is 7MPa, the pressing speed of the upper pressing plate is 4mm/min, namely the compression process can be completed within 38s, and the set compression ratio is reached. The treatment temperature can be transferred to the whole thickness layer of the treated material in the processes of preheating for 60s and compressing, heat conduction and heat progression for 38s, and the treatment effect of integral densification is formed.
In the embodiment, the materials are directly discharged after pressure relief, the carbon section with the thickness of 3.27mm is prepared.
Example 12
The treated material of this example is litchi wood with a thickness of 6mm, the drying conditions are 103 + -2 deg.C, and the water content of the treated material after weighing is 0% to 0.5%. The processing temperature was 280 ℃ and the thickness of the gauge was 5mm, so the set compression amount was 16.7%.
And (3) placing the processing material between the upper pressing plate and the lower pressing plate, rapidly descending the upper pressing plate to the surface of the upper pressing plate contacting the processing material, keeping (preheating) the upper pressing plate for 60s after contacting the surface of the processing material, and continuously pressing the upper pressing plate and applying pressure to the processing material. In the compression process, the pressure of the pressing plate is 9MPa, the pressing speed of the upper pressing plate is 1mm/min, namely 60s can finish the compression process and reach the set compression ratio. The treatment temperature can be transferred to the whole thickness layer of the treatment material in the processes of 60s preheating, 60s compression, heat conduction and heat progression, and the treatment effect of integral densification is formed.
In the embodiment, the carbon section with the thickness of 4.92mm is prepared by directly discharging after pressure relief.
Production parameters of the wood strengthening treatment methods of examples 1 to 6 are shown in table 1; production parameters of the wood strengthening treatment methods of examples 7 to 12 are shown in table 2; table 3 shows the product performance parameters of the carbon-wood composite profiles obtained by the wood strengthening treatment methods of examples 1 to 6; the product performance parameters of the carbon profiles obtained by the wood strengthening treatment methods of examples 7 to 12 are shown in table 4. The comparison groups 1 and 2 are surface-layer densified profiles prepared by the surface-layer compression technology in the prior art, and the comparison groups 3 and 4 are overall densified profiles prepared by the overall compression technology in the prior art. The compression process is implemented by adopting a flat plate type hot press, and the compression treatment temperature is 160 ℃; the plastic deformation fixing method adopts normal pressure superheated steam treatment, and the treatment temperature is 180 ℃.
TABLE 1 production parameters of the wood strengthening treatment processes of examples 1 to 6
TABLE 2 production parameters for the wood strengthening treatment processes of examples 7 to 11
TABLE 3 Properties of carbon-wood composite profiles obtained by the Wood enhancement treatment methods of examples 1 to 6
TABLE 4 product Performance parameters of carbon-wood composite profiles obtained by the Wood enhancement treatment methods of examples 7 to 11
The foregoing description is for the purpose of illustration and is not for the purpose of limitation. Many embodiments and many applications other than the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego the subject matter and should not be construed as an admission that the applicant does not consider such subject matter to be part of the disclosed subject matter.
Claims (10)
1. A method for strengthening wood, wherein a material to be treated is compressed under a predetermined treatment temperature and treatment pressure, wherein the material to be treated is in an oven-dried state, and the treatment temperature is equal to or higher than a softening temperature of the wood.
2. The wood strengthening treatment method according to claim 1, wherein the treatment temperature is 240 ℃ or higher.
3. The method of claim 1, wherein the water content of the treated material is 0 ± 1.0%.
4. The wood strengthening treatment method according to claim 1, wherein the treatment temperature is conducted from a side to another side where heat is applied in a compression direction of the treated material; at the same time, the processing temperature is advanced to the sub-thickness layer with the compression feed.
5. The wood strengthening treatment method according to claim 4, wherein the treatment temperature is advanced with the advance of the compression, while the advance enables the continuous advance of the compression with the conduction of the treatment temperature.
6. The wood strengthening treatment of claim 5, wherein the time from the first unit thickness layer to the treatment temperature to the last unit thickness layer completing the compression is less than 5 minutes.
7. The wood strengthening treatment method according to claim 1, wherein after the treated wood reaches a set compression rate, the pressure is directly released for discharging; or after pressure relief, the material is kept discharged again after the thickness of 10s to 30 s.
8. The wood strengthening treatment method according to claim 1, wherein the set compression ratio is smaller than an actual compression ratio.
9. The carbon material obtained by the wood-strengthening treatment method according to claim 1, wherein the equilibrium water content of the carbon material is 7 to 9% at 20 ℃/95% RH.
10. The carbon material as claimed in claim 9, wherein the tree species from which the carbon material is made is redwood, millettia wood, rubber wood, lychee wood, cedar wood, pine wood, poplar, paulownia, sapanwood, eucalyptus or sasanqua.
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