JP7116404B2 - Method for producing furan polymer impregnated wood - Google Patents

Description

The present invention relates to a method for producing furan polymer-impregnated lumber obtained by impregnating lumber with furfuryl alcohol and polymerizing the lumber.

Wood generally has the disadvantages of being susceptible to corrosion, being susceptible to damage by termites and the like, and being susceptible to twisting and warping. In order to compensate for such drawbacks, wood modification techniques have been proposed in which wood is resinified to improve durability and dimensional stability. One of these known techniques is to impart antiseptic performance, anti-termite performance, and dimensional stability to wood by resinifying alcohol with acid as a catalyst (polymerization initiator) in wood. . For example, Patent Literatures 1 and 2 propose methods for producing furan polymer-impregnated lumber.

In the production method described in Patent Document 1, water is mixed with a polymerization initiator such as furfuryl alcohol or maleic anhydride, and a stabilizer comprising a sodium salt of boric acid and lignosulfonic acid to prepare a polymerizable furfuryl alcohol monomer. The wood to be modified is impregnated with the mixed solution, and the impregnated wood is dried by heating to obtain the furan polymer-impregnated wood. In the production method described in Patent Document 2, a polymerizable furfuryl alcohol monomer mixture obtained by mixing water with furfuryl alcohol, a stabilizing co-solvent composed of alcohol or acetone, and a polymerization initiator such as maleic acid is prepared. , the wood to be modified is impregnated, and the impregnated wood is dried by heating to obtain the furan polymer-impregnated wood.

Japanese Patent No. 4190885 Japanese Patent No. 4841141

In Patent Documents 1 and 2, a stabilizer or a stabilizing aid is also mixed together so that the polymerization of furfuryl alcohol does not start when furfuryl alcohol and a polymerization initiator (catalyst) are mixed. The pH of the liquid is maintained neutral. As a result, the polymerization of furfuryl alcohol is suppressed in the process of impregnating the mixed aqueous solution into the wood, and the furfuryl alcohol spreads throughout the interior of the wood. In the curing process (polymerization process), the stabilizer and the stabilizing aid are evaporated and removed from the inside of the wood by heating and drying, etc., and the inside of the wood is acidified to polymerize furfuryl alcohol. .

Thus, in the conventional method for producing furan polymer-impregnated lumber, a stabilizer or a stabilizing aid is added to an aqueous solution containing furfuryl alcohol and its polymerization initiator to keep it neutral, thereby improving the storage stability of the aqueous solution. and increase the permeability to the interior of the wood. Therefore, the aqueous solution must be added with a polymerization initiator for furfuryl alcohol and a stabilizer or a stabilizing aid to suppress the polymerization. After the wood is impregnated with the aqueous solution, the wood must be dried by heating to evaporate the stabilizer and the like in order to initiate the polymerization of furfuryl alcohol. Therefore, the preparation cost of the aqueous solution is high, and the facility cost for evaporating and recovering the stabilizer from the wood is also high.

In view of these points, it is an object of the present invention to propose a method for producing furan polymer-impregnated lumber that can polymerize furfuryl alcohol inside the lumber without injecting a polymerization initiator into the lumber from the outside. be.

In order to solve the above problems, the method for producing furan polymer-impregnated wood of the present invention comprises:
A pretreatment step of heat-drying the wood under predetermined heat treatment conditions to acidify the wood and make it weakly acidic with a pH of 6 or 5 ;
Wood is impregnated with an aqueous solution that contains furfuryl alcohol and does not contain a polymerization initiator for furfuryl alcohol, and the acid generated inside the wood in the pretreatment step functions as a polymerization initiator for furfuryl alcohol. , furan polymer-impregnated lumber is produced through a furfuryl alcohol impregnation/polymerization step in which the furfuryl alcohol is polymerized.

In the method of the present invention, prior to the step of impregnating the wood with furfuryl alcohol, the wood is pretreated under predetermined heat treatment conditions to generate an acid such as acetic acid inside the wood, thereby removing the wood. making it acidic. By using the acid generated inside the wood as a polymerization initiator for furfuryl alcohol, there is no need to impregnate or inject the polymerization initiator (acid catalyst) together with furfuryl alcohol from the outside of the wood.

Therefore, an aqueous solution containing only furfuryl alcohol and water can be used as the aqueous solution containing furfuryl alcohol. Storage and management of the aqueous solution becomes extremely easy. In addition, the step of evaporating and recovering stabilizers and the like that inhibit the polymerization of furfuryl alcohol after impregnating wood with the aqueous solution is also unnecessary. Therefore, according to the method of the present invention, furan polymer-impregnated lumber can be produced at a low running cost by using an aqueous solution of furfuryl alcohol that can be prepared at low cost and an inexpensive equipment configuration.

FIG. 2 is an explanatory diagram showing an example of a manufacturing process of furan polymer-impregnated lumber to which the present invention is applied.

An example of the method for producing furan polymer-impregnated lumber to which the present invention is applied will be described below with reference to the drawings. The embodiment described below is an example of the method of the present invention, and is not intended to limit the method of the present invention to the embodiment.

The manufacturing process of furan polymer-impregnated lumber will be described with reference to FIG. The wood to be modified is, for example, Japanese cedar, Japanese cypress, Chinese pine, red pine, or the like. First, a raw wood (log) is processed into lumber having a predetermined cross-section and a predetermined length by a sawmill (sawmill step ST1).

The lumber 1 after lumber processing is subjected to pretreatment by heating and drying (pretreatment step ST2). In the pretreatment, the lumber 1 is heated and dried under predetermined heat treatment conditions. For example, the wood placed in the processing chamber 2a of the wood processing apparatus 2 is subjected to reduced pressure drying and pressure drying. A heat conditioner (Hildebrand Co., Ltd.), for example, can be used as the wood processing apparatus 2 having pressure reduction/pressure functions.

The lumber 1 is dried by heating under predetermined heat treatment conditions to impart durability and dimensional stability to the lumber 1 and to impart acidity. By appropriately setting the heat treatment conditions according to the tree species, an acid such as acetic acid (ethanoic acid) is generated inside the lumber 1 after the pretreatment, resulting in a weakly acidic state with a pH of about 6 or 5. Become. In addition, the heat drying treatment improves the impregnation property of the wood with furfuryl alcohol, and in the subsequent process, it becomes easy to uniformly impregnate the entire interior of the wood with furfuryl alcohol, and the final product is obtained. The strength and other properties of furan polymer impregnated wood can be improved.

As the heat treatment method, a method of heat-treating the lumber 1 to be treated under a normal pressure/superheated steam atmosphere, a method of heat-treating it under a high-pressure/inert gas atmosphere, etc., can be appropriately selected from various known methods. method can be adopted. In any method, the heat treatment conditions such as treatment pressure used for decompression and pressurization, decompression holding time, pressurization holding time, heating temperature, heating medium, etc. Select as appropriate according to your needs.

In addition, wood modification technology is known that improves the durability, dimensional stability, etc. of wood by heat treatment. It is commercialized under names such as "Stech Wood (registered trademark)." These heat treatment techniques can also be applied to the pretreatment step ST2 of this example.

The lumber 1 after the pretreatment is subjected to a furfuryl alcohol (FA) impregnation/polymerization step ST3. In the furfuryl alcohol impregnation/polymerization step ST3, an aqueous solution 3, which is a mixture of furfuryl alcohol and water, is used. Aqueous solution 3 of this example is a mixed solution in which furfuryl alcohol is simply mixed with water, and does not contain a polymerization initiator or other compounds. For example, a mixture of 50% by weight of furfuryl alcohol and 50% by weight of water is used. In addition, it is also possible to mix compounds other than a polymerization initiator as needed.

The aqueous solution 3 is, for example, prepared in advance and stored in the solution tank 4 . The lumber 1 is put into an injection chamber 5a of an injection device 5 having a pressurization/decompression function. The aqueous solution 3 is supplied from the solution tank 4, and the inside of the injection chamber 5a is maintained at a predetermined pressurized state, for example, 15 atm, for a predetermined time. As a result, the aqueous solution 3 spreads sufficiently to the interior of the lumber 1 . After that, the surplus aqueous solution 3 is recovered, the injection chamber 5a is evacuated to a predetermined reduced pressure state, and the injection chamber 5a is maintained in this state for a predetermined time to remove the aqueous solution 3. The impregnated wood 1 is dried.

In this process, the furfuryl alcohol in the aqueous solution 3 is polymerized by reacting with an acid such as acetic acid generated inside the lumber 1 while impregnating the lumber 1 with the furfuryl alcohol. Furfuryl alcohol spreads throughout the wood 1 as it polymerizes. As a result, the furan polymer-impregnated lumber 10 whose interior is filled with the furfuryl alcohol polymer (furan polymer) (resinized state) is obtained.

Also in this step, various known methods can be used as a method for impregnating the lumber 1 with the aqueous solution 3 . For example, the lumber 1 may be impregnated with the aqueous solution 3 through a decompression step and a pressurization step by a vacuum pressure impregnation method. In any method, the treatment conditions such as treatment pressure and holding time may be appropriately set according to the tree species, wood size, target impregnation amount (injection amount) of the aqueous solution 3, and the like.

After that, the furan polymer-impregnated lumber 10 is subjected to a post-drying step ST4. In the post-drying step ST4, the furan polymer-impregnated lumber 10 is dried for a predetermined period of time at a temperature of 100° C. under reduced pressure using a lumber drying device 8 having pressure and pressure reduction functions. Drying under reduced pressure lowers the boiling point and allows drying at a lower heating temperature, which is advantageous in reducing drying time and costs.

The dried furan polymer-impregnated lumber 10 is molded into a predetermined size and shape by a wood molding machine (forming step ST5). As a wood molding machine, for example, a Weinig molder (Michael Weinig Japan Co., Ltd.) can be used.

ST1 lumber process ST2 pretreatment process ST3 furfuryl alcohol impregnation/polymerization process ST4 post-drying process ST5 molding process 1 wood 2 wood treatment device 2a treatment chamber 3 aqueous solution 4 solution tank 5 injection device 5a injection chamber 8 wood drying device 10 furan polymer impregnation wood

Claims (7)

a pretreatment step of heat-drying the lumber under predetermined heat treatment conditions to acidify the lumber to a weakly acidic pH of 6 or 5 ;
The wood is impregnated with an aqueous solution that contains furfuryl alcohol and does not contain a polymerization initiator for furfuryl alcohol, and the acid generated inside the wood in the pretreatment step is a polymerization initiator for the furfuryl alcohol. and a furfuryl alcohol impregnation and polymerization step in which the furfuryl alcohol polymerizes,
A method for producing furan polymer impregnated wood comprising: A method for producing furan polymer impregnated wood according to claim 1, wherein said acid is at least acetic acid. 3. The method for producing a furan polymer-impregnated lumber according to claim 1, wherein in the furfuryl alcohol impregnation/polymerization step, the lumber is impregnated with the aqueous solution obtained by mixing only furfuryl alcohol and water. The method for producing furan polymer-impregnated wood according to claim 1 or 2, wherein the aqueous solution contains 50 wt% furfuryl alcohol and 50 wt% water. 5. The method for producing a furan polymer-impregnated lumber according to any one of claims 1 to 4, wherein in the furfuryl alcohol impregnation/polymerization step, the lumber is impregnated with the aqueous solution under 15 atmospheres. 6. The method for producing furan polymer-impregnated wood according to any one of claims 1 to 5, further comprising a post-drying step of drying the wood after the furfuryl alcohol impregnation and polymerization step. 7. The method for producing furan polymer-impregnated lumber according to claim 6, wherein in the post-drying step, the lumber is dried in an atmosphere of 100[deg.] C. under reduced pressure.

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